KR20120061511A - Organic Light Emitting Diode Display Device Having A Reflective Electrode And Method For Manufacturing The Same - Google Patents

Abstract

PURPOSE: An organic electroluminescence display device and a manufacturing method thereof are provided to improve reflectivity of a cathode by including a structure in which a reflective electrode layer and a transparent conductive layer are successively laminated on cathode and pad parts. CONSTITUTION: A scan line, a data line(DL), and a driving current line(VDD) define a pixel region on a substrate. A thin film transistor(DRT) is formed within the pixel region. A pad is formed on one end side of the scan line, the data line, and the driving current line. A pad terminal is formed on the upper part of the pad and a cathode formed within the pixel region by being connected to the thin film transistor. A reflective electrode layer and a transparent conductive layer are laminated on cathode and pad terminals.

Description

Organic Light Emitting Diode Display Device Having A Reflective Electrode And Method For Manufacturing The Same}

The present invention relates to an organic light emitting display device having a reflective electrode and a method of manufacturing the same. In particular, the present invention relates to an organic light emitting display device of a top emission type, and includes a reflective electrode in a lower electrode layer to send light emitted from the organic layer to the top without loss, and includes the reflective electrode in the pad part. The present invention relates to an organic light emitting display device and a method of manufacturing the same, which prevent a short circuit in a pad part even when a transparent electrode is formed thin.

2. Description of the Related Art Recently, various flat panel display devices capable of reducing weight and volume, which are disadvantages of cathode ray tubes (CRTs), have been developed. Such flat panel displays include liquid crystal displays (LCDs), field emission displays (FEDs), plasma display panels (PDPs), and electroluminescence devices (ELs). have.

Electroluminescent devices are classified into inorganic electroluminescent devices and organic light emitting diode devices according to the material of the light emitting layer. As the self-emitting devices emit light by themselves, they have fast response speed, high luminous efficiency, high luminance and viewing angle. 1 is a view showing the structure of an organic light emitting diode. The organic light emitting diode includes an organic electroluminescent compound layer electroluminescent as shown in FIG. 1, and a cathode and an anode facing each other with the organic electroluminescent compound layer interposed therebetween. The organic electroluminescent compound layer includes a hole injection layer (HIL), a hole transport layer (HTL), an emission layer (EML), an electron transport layer (ETL), and an electron injection layer (Electron injection). layer, EIL).

An organic light emitting diode emits light due to energy from the excitons in the excitation process when holes and electrons injected into the anode and the cathode recombine in the emission layer EML. The organic light emitting diode display displays an image by electrically controlling the amount of light generated from the light emitting layer EML of the organic light emitting diode as shown in FIG. 1.

The organic light emitting diode display (OLED), which utilizes the characteristics of an organic light emitting diode (OLED), has a passive matrix type organic light emitting diode display (PMOLED) and an active matrix. It is roughly classified into an active matrix type organic light emitting diode display (AMOLED). In addition, there is a top-emission method and a bottom-emission method according to the direction in which light is emitted.

An active matrix type flexible organic light emitting diode display (Flexible AMOLED) displays an image by controlling a current flowing through the organic light emitting diode using a thin film transistor (TFT). In order to secure the rigidity and flexibility of the substrate at the same time, since the TFT and the organic light emitting diode are formed on the thin foil-like metal thin film, an upper light emission method emitting light upward of the substrate is used. For the top emission method, an inverted organic light emitting diode (Inverted OLED, hereinafter referred to as "IOD") that forms an organic compound layer for electroluminescence on the cathode is known as the most suitable structure.

In the organic light emitting display device, the cathode may use indium tin oxide (ITO), which is a transparent electrode satisfying a work function condition. However, in the top emission method, since light must be emitted from the cathode toward the anode, it is preferable to use a reflective electrode under the cathode. As such, functional and structural conditions conflict with each other, a solution is needed to solve this problem.

SUMMARY OF THE INVENTION An object of the present invention is to overcome the problems of the prior art, and to provide an organic light emitting display device having a reflective electrode for reflecting light upwards under a transparent electrode satisfying a work function condition and a method of manufacturing the same. There is. Another object of the present invention is to provide an organic light emitting display device having a reflective electrode having a thin thickness of a transparent electrode in a top emission type organic light emitting display device and improving reflection efficiency, and a method of manufacturing the same. . Still another object of the present invention is to provide an organic light emitting display device having a reflective electrode having improved contact resistance even when the thickness of the transparent electrode is reduced because the pad electrode has the same structure as the cathode even when the transparent electrode is thinly formed. It is providing the manufacturing method. Another aspect of the present invention is to provide a method of manufacturing an organic light emitting display device having a cathode including a transparent electrode and a reflective electrode and a reflective electrode that simplifies a mask process.

An organic light emitting display device according to the present invention includes a substrate; Scan wiring, data wiring and driving current wiring defining a pixel region on the substrate; A thin film transistor formed in the pixel region; A pad formed at one end of the scan line, the data line, and the driving current line; And a pad terminal connected to the thin film transistor in the pixel region and a pad terminal formed on the pad, wherein the cathode and the pad terminal are formed by stacking a reflective electrode layer and a transparent conductive layer.

The reflective electrode layer has a thickness of at least 500 GPa; The transparent conductive layer is characterized by having a thickness of less than 300 kPa.

The reflective electrode layer has a thickness of 1000 to 1500 kPa; The transparent conductive layer is characterized by having a thickness of 50 ~ 100 ~.

The reflective electrode layer includes at least one of aluminum, neodium, nickel, titanium, tantalum, copper, silver, and aluminum alloys. Characterized in that.

The transparent conductive layer may include at least one of indium tin oxide (ITO) and indium zinc oxide (IZO).

The pad includes a gate pad formed at one end of the scan wiring, and a data pad formed at one end of the data wiring and the driving current wiring; The pad terminal may include a gate pad terminal formed on the gate pad and a data pad terminal formed on the data pad.

The thin film transistor may include a switching thin film transistor and a driving thin film transistor.

The switching thin film transistor includes a switching gate electrode branching from the scan line, a switching source electrode branching to the data line, and a switching drain electrode facing the switching source electrode; The driving thin film transistor may include a driving gate electrode in contact with the switching drain, a driving source electrode branching from the driving current line, and a driving drain electrode facing the driving source electrode and connected to the cathode.

In addition, a method of manufacturing an organic light emitting display device according to the present invention includes: forming a scan wiring, a data wiring, a driving current wiring, and a thin film transistor disposed in the pixel region on a substrate; A reflective electrode layer and a transparent electrode layer are continuously deposited and patterned in the pixel area on the substrate to form a cathode connected to the thin film transistor, and a pad terminal connected to one end of the scan line, the data line, and the driving current line. It includes a step.

The reflective electrode layer has a thickness of at least 500 GPa; The transparent conductive layer is characterized by having a thickness of less than 300 kPa.

The reflective electrode layer has a thickness of 1000 to 1500 kPa; The transparent conductive layer is characterized by having a thickness of 50 ~ 100 ~.

The reflective electrode layer includes at least one of aluminum, neodium, nickel, titanium, tantalum, copper, silver, and aluminum alloys. Characterized in that.

The transparent conductive layer may include at least one of indium tin oxide (ITO) and indium zinc oxide (IZO).

The forming of the thin film transistor may include applying a gate metal on the substrate to form a gate mask including a switching gate electrode, the scan wiring, a gate pad connected to one end of the scan wiring, and a driving gate electrode. fair; A gate insulating film, a semiconductor material, and an impurity semiconductor material are coated on the gate element to form a switching semiconductor layer and a switching ohmic contact layer overlapping the switching gate electrode, and a driving semiconductor layer and a driving ohmic contact layer overlapping the driving gate electrode. And a second mask process of exposing a portion of the driving gate electrode; And applying a source metal to branch the data wiring, the switching source electrode branching from the data wiring, the switching data electrode facing the switching source electrode and in contact with the driving gate electrode, the driving current wiring, and the driving current wiring. Forming a switching thin film transistor and a driving thin film transistor by forming a driving source electrode, a driving drain electrode facing the driving source electrode and in contact with the cathode, and a data pad connected to one end of the data line and the driving current line. It is characterized by including a third mask process.

The forming of the cathode and the pad terminal may include applying and patterning a planarization layer on the substrate on which the switching thin film transistor and the driving thin film transistor are formed to expose the driving drain electrode, the gate pad, and the data pad. 4 mask process; The reflective electrode layer and the transparent conductive layer are sequentially applied to the planarization layer and simultaneously patterned to form the cathode connected to the driving drain electrode, the gate pad terminal connected to the gate pad, and the data pad terminal connected to the data pad. And a fifth mask process.

Forming an organic light emitting layer on the cathode; And forming an anode on the organic light emitting layer.

The present invention includes a cathode in which a reflective electrode layer and a transparent conductive layer are sequentially stacked, and an organic light emitting display of a top emission type that efficiently reflects light generated from an organic light emitting layer interposed between a lower cathode and an upper anode to an upper portion thereof. Get the device. In addition, the present invention has a structure in which the reflective electrode layer and the transparent conductive layer are sequentially stacked in the pad part in the same way as the cathode, and even if the transparent conductive layer is thinly stacked, defects such as a decrease in contact resistance or disconnection in the pad part occur. I never do that. As a result, a thin transparent conductive layer can be formed, and accordingly, a top emission type organic light emitting display device having improved reflectivity at the cathode can be obtained. In addition, by sequentially depositing and simultaneously patterning the reflective electrode layer and the transparent electrode layer constituting the cathode and pad portions, a simple organic electroluminescent display device may be manufactured without an additional mask process.

1 is a view showing the structure of an organic light emitting diode.
2 is a plan view showing the structure of an organic light emitting diode display according to the present invention;
3A to 3F are cross-sectional views taken along the line II ′ of FIG. 1 to illustrate a process of manufacturing an organic light emitting diode display according to the present invention.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings. 2 is a plan view illustrating a structure of an organic light emitting display device according to an exemplary embodiment of the present invention. 3A to 3F are cross-sectional views taken along the line II ′ of FIG. 1 to illustrate a process of manufacturing the organic light emitting display device according to the present invention.

Referring to FIG. 2, an active matrix organic light emitting diode display device as an example of a top emission type organic light emitting diode is described. The organic light emitting diode display according to the present invention includes a switching TFT (SWT), a driving TFT (DRT) connected with the switching TFT, and an organic light emitting diode (OLED) connected to the driving TFT (DRT).

In the case of a flexible organic light emitting diode display, the substrate is made of a thin metal thin film such as stainless steel or aluminum in order to have both rigidity and flexibility. In addition, when the devices are directly formed on the metal substrate, electrical problems may occur. Therefore, it is preferable to apply the insulating film or the planarization film to the entire surface using an inorganic insulating material such as SiNx.

The switching TFT SWT is formed at the intersection of the scan line SL and the data line DL. The switching TFT SWT functions to select a pixel. The switching TFT SWT includes a switching gate electrode WG branching from the scan line SL, a switching semiconductor layer WA, a switching source electrode WS, and a switching drain electrode WD.

The driving TFT DRT serves to drive the organic light emitting diode OLED of the pixel selected by the switching TFT SWT. The driving TFT DRT includes the driving gate electrode RG connected to the switching drain electrode WD, the driving semiconductor layer RA, the driving source electrode RS connected to the driving current wiring VDD, and the driving drain electrode RD. ). The driving drain electrode RD is connected to the cathode of the organic light emitting diode OLED.

The scan line SL running in the horizontal direction and the data line DL running in the vertical direction cross each other to define a rectangular pixel area. A gate pad GP for receiving a scan signal is formed at one end of the scan line SL. The gate pad GP contacts the gate pad terminal GPT through the gate pad contact hole GPH from which a portion of the insulating layer covering the gate pad GP is removed.

Further, at one end of the data line DL, a data pad DP for receiving the cathode voltage and the data voltage of the image data is formed. The data pad DP contacts the data pad terminal DPT through the data pad contact hole DPH from which a portion of the insulating layer covering the data pad DP is removed.

In the organic light emitting diode display according to the present invention, the cathode constituting the organic light emitting diode OLED, the gate pad terminal GPT, and the data pad terminal DPT have a two-layer structure in which a reflective electrode layer and a transparent conductive layer are stacked. 3A to 3F, the structure of the organic light emitting diode according to the present invention and the process of manufacturing the organic light emitting diode display according to the present invention will be described in more detail.

A gate metal is deposited on the substrate SUB and patterned by a first mask process to form a gate element. The gate element may include a scan wiring SL, a switching gate electrode WG branched from the scan wiring SL to a pixel region, a gate pad GP formed at one end of the scan wiring SL, and an inner portion of the pixel region. Gate electrodes DG of the formed driving TFT DRT are included (FIG. 3A).

On the entire surface of the substrate SUB on which the gate element is formed, a gate insulating film GI is formed. A semiconductor material and a semiconductor material doped with impurities are successively deposited on the gate insulating layer GI. In the second mask process, the semiconductor material and the semiconductor material doped with impurities are patterned to form a switching semiconductor channel layer WA and a switching ohmic contact layer Wn overlapping the switching gate electrode WG.

At the same time, the driving semiconductor channel layer RA and the driving ohmic contact layer Rn overlapping a portion of the driving gate electrode RG are formed. The gate contact hole GH exposing a portion of the driving gate electrode RG not overlapping the driving semiconductor channel layer RA and the driving ohmic contact layer Rn is formed. In order to simultaneously pattern regions having different levels of patterning, it is preferable to use a half-tone mask in the second mask process (FIG. 3B).

The source metal material is deposited on the entire surface of the substrate SUB on which the channel layers WA and RA are formed and patterned by a third mask process to form a source-drain element. The source-drain element includes a switching source electrode which is branched from the data line DL, the driving current line VDD, and the data line DL, which is orthogonal to the scan line SL, and contacts one side of the switching ohmic contact layer Wn. The driving source electrode DS, which is branched from the WS and the driving current wiring VDD, contacts one side of the driving ohmic contact layer Dn, and the switching ohmic contact layer facing each other at a predetermined distance from the switching source electrode WS. Wn) includes a driving drain electrode RD contacting the other side of the switching drain electrode WD and the driving source electrode DS at a predetermined distance, and contacting the other side of the driving ohmic contact layer Rn.

In this case, the switching drain electrode WD contacts the driving gate electrode RG exposed through the gate contact hole GH formed in the gate insulating layer GI. In addition, a data pad DP is formed at one end of the data line DL and the driving current line VDD. The exposed portion between the switching source electrode WS and the switching drain electrode WD in the switching ohmic contact layer Wn and the driving source electrode in the driving ohmic contact layer Rn are formed using the formed source-drain element as a mask. The exposed portion between the RS and the driving drain electrode RD is removed. This completes the switching TFT (SWT) and the driving TFT (DRT) (Fig. 3C).

The passivation film PAS and the planarization film PL are successively coated on the entire surface of the substrate SUB including the switching TFT SWT and the driving TFT DRT. In the fourth mask process, the planarization layer PL, the passivation layer PAS, and / or the gate insulating layer GI are patterned to form contact holes. In the contact holes, a portion of the planarization layer PL and the passivation layer PAS is removed to expose a portion of the driving drain electrode RD and a data pad contact hole exposing the data pad DP. DPH). In addition, the planarization layer PL, the passivation layer PAS, and the gate insulation layer GI are partially removed to include the gate pad contact hole GPH exposing the gate pad GP (FIG. 3D).

The reflective electrode layer AL and the transparent conductive layer IT are successively deposited on the entire surface of the substrate SUB on which the contact holes are formed. The reflective electrode layer AL is any one selected from aluminum, neodium, nickel, titanium, tantalum, copper, or silver, or AlNd and An alloy containing two or more of the above materials, such as AlNi, is included. The transparent conductive layer (IT) includes indium tin oxide (ITO) or indium zinc oxide (IZO).

In the fifth mask process, the reflective electrode layer AL and the transparent conductive layer IT are simultaneously patterned to form the cathode CAT, the gate pad terminal GPT, and the data pad terminal DPT. The cathode CAT contacts the driving drain electrode RD exposed through the drain contact hole DH. The gate pad terminal GPT contacts the gate pad GP through the gate pad contact hole GPH, and the data pad terminal DPT contacts the data pad DP through the data pad contact hole DPH. The cathode CAT, the gate pad terminal GPT, and the data pad terminal DPT according to the present invention all have a two-layer structure in which the reflective electrode layer AL and the transparent conductive layer IT are stacked (FIG. 3E).

On the substrate SUB on which the cathode CAT and the pad terminals GPT and DPT are formed, a bank BANK is formed in an area excluding the effective pixel area and the pad terminals. The organic light emitting material OL is formed on the cathode CAT exposed between the banks BANK. The organic light emitting material OL may be formed of a multilayer organic film to have a structure as shown in FIG. 1. In addition, a transparent conductive material is deposited on the organic light emitting material OL to form an anode ANO. In this case, the anode ANO may be formed to cover the bank BANK so that the anodes ANO of all the pixel regions are connected to one (FIG. 3F).

The thinner the transparent conductive material such as ITO and IZO, the higher the transparency. Therefore, in the top emission type organic light emitting diode display device as in the present invention, the higher the transparency of the transparent conductive material used as the cathode, the higher the luminance. However, when the reflective electrode layer is formed only on the cathode or when the transparent conductive layer is used alone, when the transparent conductive layer is thinly formed to improve the brightness, the gate pad terminal and the data pad terminal may be thinly formed. At this time, contact resistance may increase in the pad terminal portion, or a defect such as disconnection may occur. Therefore, there is a limit to thinning the transparent conductive layer.

However, in the present invention, not only the cathode CAT, but also the gate pad terminal GPT and the data pad terminal DPT include the reflective electrode layer AL and the transparent electrode layer IT. Therefore, even when the transparent electrode layer IT is formed to a minimum thickness, the presence of the reflective electrode layer AL does not cause problems such as an increase in contact resistance or disconnection in the pad terminal portion. Therefore, the transparent electrode layer IT may be thinned at the cathode CAT to maximize the reflection efficiency of the reflective electrode layer AL.

For example, when the pad terminal is formed only of the transparent conductive layer, the pad terminal should have a thickness of 1000 kPa or more in order to prevent contact resistance problems and disconnection problems. However, in the present invention, when the reflective electrode layer AL having a thickness of 500 to 1000 kPa is deposited first, and then the transparent conductive layer IT of 300 kPa or less is formed, there is no problem of contact resistance or disconnection in the pad terminal portion. In addition, the reflection efficiency increases at the cathode CAT.

In addition, in order to maximize the reflection efficiency of the reflective electrode layer AL while ensuring the work function of the cathode CAT, the transparent conductive layer IT may be formed to have a thickness of about 50 to about 100 GPa. In this case, it is preferable to form the reflective electrode layer AL at 1000 to 1500 kPa in order to prevent contact resistance problems or disconnection problems at the pad terminal portion.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification but should be defined by the claims.

SUB: Substrate SL: Scan Wiring
DL: data wiring VDD: drive current wiring
SWT: Switching Thin Film Transistor DRT: Driving Thin Film Transistor
WG: switching gate electrode WA: switching channel layer
Wn: switching ohmic contact layer WS: switching source electrode
WD: switching drain electrode GH: gate contact hole
GP: Gate Pad GPH: Gate Pad Contact Hole
GPT: gate pad terminal GI: gate insulating film
RG: driving gate electrode RA: driving channel layer
Rn: drive ohmic contact layer RS: drive source electrode
RD: driving drain electrode DH: drain contact hole
DP: data pad DPH: data pad contact hole
DPT: data pad terminal PAS: protective film
PL: planarization film CAT: cathode
OL: organic light emitting film ANO: anode
OLED: organic light emitting diode BANK: bank

Claims (16)

Board;
Scan wiring, data wiring and driving current wiring defining a pixel region on the substrate;
A thin film transistor formed in the pixel region;
A pad formed at one end of the scan line, the data line, and the driving current line; And
An organic light emitting display device comprising a cathode connected to the thin film transistor and a pad terminal formed on the pad, wherein the cathode and the pad terminal are stacked with a reflective electrode layer and a transparent conductive layer; .
The method of claim 1,
The reflective electrode layer has a thickness of at least 500 GPa;
The transparent conductive layer has an organic light emitting display device having a thickness of less than 300Å.
The method of claim 2,
The reflective electrode layer has a thickness of 1000 to 1500 kPa;
The transparent conductive layer has an organic light emitting display device having a thickness of 50 ~ 100Å.
The method of claim 1,
The reflective electrode layer includes at least one of aluminum, neodium, nickel, titanium, tantalum, copper, silver, and aluminum alloys. An organic light emitting display device, characterized in that.
The method of claim 1,
The transparent conductive layer includes at least one of indium tin oxide (ITO) and indium zinc oxide (IZO).
The method of claim 1,
The pad includes a gate pad formed at one end of the scan wiring, and a data pad formed at one end of the data wiring and the driving current wiring;
The pad terminal includes a gate pad terminal formed on the gate pad and a data pad terminal formed on the data pad.
The method of claim 1,
The thin film transistor includes an switching thin film transistor and a driving thin film transistor.
The method of claim 7, wherein
The switching thin film transistor includes a switching gate electrode branching from the scan line, a switching source electrode branching to the data line, and a switching drain electrode facing the switching source electrode;
The driving thin film transistor may include a driving gate electrode in contact with the switching drain, a driving source electrode branching from the driving current line, and a driving drain electrode facing the driving source electrode and connected to the cathode. Electroluminescent display.
Forming a scan wiring, a data wiring, a driving current wiring, and a thin film transistor disposed in the pixel region on the substrate; And,
A reflective electrode layer and a transparent electrode layer are continuously deposited and patterned in the pixel area on the substrate to form a cathode connected to the thin film transistor and a pad terminal connected to one end of the scan line, the data line, and the driving current line. An organic light emitting display device manufacturing method comprising the steps of.
The method of claim 9,
The reflective electrode layer has a thickness of at least 500 GPa;
The transparent conductive layer has a thickness of less than 300 GPa manufacturing method of an organic light emitting display device.
11. The method of claim 10,
The reflective electrode layer has a thickness of 1000 to 1500 kPa;
The transparent conductive layer has a thickness of 50 ~ 100Å of the organic light emitting display device manufacturing method.
The method of claim 9,
The reflective electrode layer includes at least one of aluminum, neodium, nickel, titanium, tantalum, copper, silver, and aluminum alloys. An organic light emitting display device manufacturing method characterized in that.
The method of claim 9,
The transparent conductive layer may include at least one of indium tin oxide (ITO) and indium zinc oxide (IZO).
The method of claim 9,
The thin film transistor forming step,
Applying a gate metal on the substrate to form a gate element including a switching gate electrode, the scan wiring, a gate pad connected to one end of the scan wiring, and a driving gate electrode;
A gate insulating film, a semiconductor material, and an impurity semiconductor material are coated on the gate element to form a switching semiconductor layer and a switching ohmic contact layer overlapping the switching gate electrode, and a driving semiconductor layer and a driving ohmic contact layer overlapping the driving gate electrode. And a second mask process of exposing a portion of the driving gate electrode; And
A source metal is coated to branch off the data wiring, the switching source electrode branching from the data wiring, the switching data electrode facing the switching source electrode and in contact with the driving gate electrode, the driving current wiring, and the driving current wiring. A driving source electrode, a driving drain electrode facing the driving source electrode and in contact with the cathode, and a data pad connected to one end of the data line and the driving current line are formed to complete a switching thin film transistor and a driving thin film transistor. A method of manufacturing an organic light emitting display device comprising a third mask process.
15. The method of claim 14,
Forming the cathode and the pad terminal,
A fourth mask process of exposing and driving the planarization layer on the substrate on which the switching thin film transistor and the driving thin film transistor are formed to expose the driving drain electrode, the gate pad, and the data pad; And
The reflective electrode layer and the transparent conductive layer are sequentially applied to the planarization layer and simultaneously patterned to form the cathode connected to the driving drain electrode, the gate pad terminal connected to the gate pad, and the data pad terminal connected to the data pad. A method of manufacturing an organic light emitting display device, the method comprising a fifth mask process.
The method of claim 9,
Forming an organic light emitting layer on the cathode; And
A method of manufacturing an organic light emitting display device, the method comprising: forming an anode on the organic light emitting layer.

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