KR100721955B1 - Electro Luminescence Device - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic light emitting display device, and more particularly, a device defect such as an organic film or an upper electrode stacked on the pixel definition layer pattern by alleviating the taper angle of the pixel definition layer pattern formed on the substrate. The present invention relates to an organic light emitting display device capable of preventing the damage and improving the image quality.

Pixel Definition Film Pattern, Reflow, Taper Angle, Organic Film

Description

Organic Luminescence Device

1 is a cross-sectional view of a conventional organic light emitting display device.

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

3 is a cross-sectional view taken along line AA ′ of FIG. 2, and is a cross-sectional view of a top-emitting organic light emitting display device according to the present invention.

4A through 4I are cross-sectional views sequentially illustrating a process of manufacturing a top-emitting organic light emitting display device according to the present invention.

5A and 5B are scanning electron micrographs of the pixel definition layer pattern before and after the pixel definition layer pattern according to the present invention is heat-treated at Tg (glass transition temperature).

           <Explanation of symbols for the main parts of the drawings>

1. Scan Line 2. Data Line

3. Common Power Line 5. Switching Thin Film Transistor

6. Driving thin film transistor 7. Capacitor

8. Lower electrode 9. Pixel part

100, 200. Substrate 110, 210. Buffer layer

120, 220. Gate insulating films 130, 230. Semiconductor layer

132, 232. Source area 134, 234. Channel area

136, 236. Drain regions 138, 238. Gate electrode

140, 240. Interlayer insulating film 150, 250. Flattening film

152, 252. Source electrode 154, 254 Drain electrode

156, 158, 256, 258. Contact holes 160, 265. Via holes

165, 270. Lower electrodes 170, 280, 280a. Pixel Definition Film Pattern

180, 290. Organic film 190, 300. Upper electrode

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic light emitting display device, and more particularly, a device defect such as an organic film or an upper electrode stacked on the pixel definition layer pattern by alleviating the taper angle of the pixel definition layer pattern formed on the substrate. The present invention relates to an organic light emitting display device capable of preventing the damage and improving the image quality.

In general, an organic light emitting display device injects electrons and holes from an electron injection electrode and a hole injection electrode into an emission layer, respectively, A light emitting display that emits light when an exciton in which electrons and holes are combined falls from an excited state to a ground state.

Due to this principle, unlike the conventional liquid crystal thin film display device, since a separate light source is not required, the volume and weight of the device can be reduced.

The method of driving the organic light emitting display device may be classified into a passive matrix type and an active matrix type.

The passive matrix type organic light emitting display device has a simple structure and a simple manufacturing method. However, the passive matrix type organic light emitting display device has a high power consumption and a large area of the display device, and the opening ratio decreases as the number of wires increases.

Therefore, the passive matrix type organic light emitting display device is used for a small display device, while the active matrix type organic light emitting display device is used for a large area display device.

In addition, the organic light emitting display device may be divided into a bottom light emitting structure and a front light emitting structure according to the direction in which light generated from the organic light emitting layer is emitted. The back light emitting structure emits light toward the formed substrate. A reflective film is formed and a transparent electrode is formed as a lower electrode. Here, when the organic light emitting display device adopts an active matrix method in which a thin film transistor is formed, a portion where the thin film transistor is formed may not transmit light, thereby reducing the area where light can be emitted. On the other hand, in the front light emitting structure, since the transparent electrode is formed as the upper electrode and the reflecting electrode or the reflecting film is formed as the lower electrode, the light is emitted in a direction opposite to the substrate side, so that the area through which light is transmitted can be improved, thereby improving luminance. have. Currently, attention has been paid to a double-sided organic light emitting display device capable of simultaneously emitting top and bottom emission on a single substrate.

Hereinafter, a conventional technology will be described with reference to the accompanying drawings.

1 is a cross-sectional view of a conventional organic light emitting display device.

Referring to FIG. 1, a polysilicon film is formed by depositing and crystallizing a buffer layer 110 on the substrate 100 and amorphous silicon on the buffer layer 110. Then, the polysilicon layer is patterned to form a semiconductor layer 130. Thereafter, a gate insulating layer 120 is deposited on the substrate 100.

A gate metal is deposited on the gate insulating layer 120, and the gate metal is patterned to form a gate electrode 138 on the gate insulating layer 120 on the semiconductor layer 130. In addition, the source region 132 and the drain region 136 are formed by using the gate electrode 138 as a mask to dope a conductive impurity. An impurity doped region between the source region 132 and the drain region 136 serves as the channel region 134.

An interlayer insulating layer 140 formed of an oxide film is formed on the substrate 100 on which the source region 132 and the drain region 136 are formed, and the interlayer insulating layer 140 is photo-etched to form a source region 132 and a drain region. Contact holes 156 and 158 exposing a portion of 136 are formed.

After depositing a conductive material on the interlayer insulating layer 140 including the contact holes 156 and 158, the conductive material is patterned to contact the source electrode 152 connected to the source region 132 through the contact hole 156. A drain electrode 154 is formed to be connected to the drain region 136 through the hole 158.

The planarization layer 150 is deposited on the substrate 100 on which the source / drain electrodes 152 and 154 are formed, and either the source electrode 152 or the drain electrode 154 is formed on the planarization layer 150. A via hole 160 exposing a portion of the drain electrode 154 is formed. This is to connect the lower electrode 165 and the drain electrode 154 to be formed in a subsequent process.

After depositing a lower electrode material on the planarization layer 150 including the via hole 160, the lower electrode material is patterned to form a lower electrode 165 connected to the drain electrode 154 through the via hole 160. do.

The pixel defining layer pattern 170 exposing a part of the surface of the lower electrode 165 and the organic layer 180 including at least an organic light emitting layer are formed on the formed lower electrode 165. Subsequently, an upper electrode 190 is formed as a transparent electrode on the organic layer 180.

However, in the conventional organic light emitting display device, as described above, after forming the lower electrode 165, the pixel defining layer pattern 170 is formed on the lower electrode 165 and defines the emission region. Formed by forming the organic layer 180 and the upper electrode 190 on the pattern 170. When the organic light emitting display device is driven, the lower electrode 165 and the pixel defining layer pattern 170 are formed. The edge portion formed has a tapered shape, and as the taper angle increases, a problem arises in that the organic layer 180 formed on the top floats or an open defect occurs. As a result, there is a problem that the lifetime of the display device is shortened.

In particular, when the organic layer 180 is formed by laser thermal transfer method (LITI), the larger the taper angle of the pixel definition layer pattern 170 is, the more open defects occur due to the organic layer 180. have.

The present invention is to solve the above-mentioned problems of the prior art, and after forming the pixel definition layer pattern, the pixel definition layer pattern is heat-treated at a glass transition temperature (Tg) for a predetermined time to form the pixel definition layer pattern. It is an object of the present invention to solve the problem that the organic film formed on the upper side is lifted or an open defect is generated by lowering the taper angle of the pixel definition layer pattern at the edge portion by reflowing.

In order to achieve the above object, the organic light emitting display device according to the present invention,

Providing a substrate having a device;

Forming a lower electrode on the substrate;

Forming a pixel definition layer pattern such that an opening is formed over the lower electrode;

Heat treating the substrate to reflow the pixel definition layer pattern; And

Forming an organic layer and an upper electrode including at least an organic light emitting layer on the lower electrode and the pixel defining layer pattern; and a method of manufacturing an organic light emitting display device comprising:

Reflowing the pixel definition layer pattern by heat-treating the substrate, characterized in that the heat treatment at the Tg (glass transition temperature) of the material constituting the pixel definition layer pattern,

And recursing the pixel definition layer pattern after the reflowing of the pixel definition layer pattern above a Tg (glass transition temperature) temperature of a material constituting the pixel definition layer pattern.

The reflowing of the pixel definition layer pattern by heat treating the substrate may include heat treating the pixel definition layer pattern for 50 to 90 minutes using polyimide.

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

Although the present invention will be described with respect to a top-emitting organic light emitting display device, the present invention is not limited thereto and may be similarly applied to a bottom-emitting organic light emitting display device and a double-sided organic light emitting display device.

2 is a plan view of a unit pixel of an organic light emitting display device according to the present invention, and FIG. 3 is a cross-sectional view taken along line AA ′ of the unit pixel of FIG. 2, and a cross-sectional view of the organic light emitting display device according to the present invention. 4A through 4I are cross-sectional views sequentially illustrating a process of manufacturing an organic light emitting display device according to an exemplary embodiment of the present invention, and FIGS. 5A and 5B illustrate a pixel definition layer pattern of Tg (glass). Scanning electron micrographs of the pixel definition film pattern before and after the heat treatment at the (transition temperature).

The present invention will be described with respect to the active matrix method of the top emission type as an embodiment, but is not necessarily limited to this, but may be applied to the active matrix method and the passive matrix method of the bottom emission type.

Referring to FIG. 2, the scan lines 1 arranged in one direction, the data lines 2 intersecting while insulated from the scan lines 1, and the data lines 2 intersecting while insulated from the scan lines 1, The common power supply line 3 is located parallel to 2). The scan line 1, the data line 2, and the common power supply line 3 represent one of a plurality of unit pixels, for example, one of red (R), green (G), and blue (B). It is defined as a unit pixel.

Accordingly, the unit pixel includes a data signal applied to the data line 2 according to a signal applied to the scan line 1, for example, a data voltage and a voltage difference applied to the common power supply line 3. The capacitor 7 which accumulates the charge and the signal generated by the charge accumulated in the capacitor 7 are input to the driving thin film transistor 6 through the switching thin film transistor 5. Subsequently, the driving thin film transistor 6 receiving the data signal sends an electrical signal to the organic light emitting display device 9 including the lower electrode 8, the upper electrode, and the organic layer including at least an organic light emitting layer between the two electrodes. To emit light.

As shown in FIG. 3 and FIG. 4A, the organic light emitting display device according to the present invention selectively forms the buffer layer 210 to a predetermined thickness on a substrate 200 made of a material such as glass, synthetic resin, or stainless steel. Form. In this case, the buffer layer 210 prevents the diffusion of impurities in the substrate 200 during the crystallization process of amorphous silicon formed in a subsequent process.

Next, as shown in FIG. 4B, after depositing amorphous silicon (not shown) to a predetermined thickness on the buffer layer 210, the amorphous silicon is crystallized and patterned by a photolithography process to form a semiconductor layer 230. ) And depositing a gate insulating layer 220 on the entire surface of the substrate 200. In this case, the gate insulating film 220 may be formed using a silicon oxide film (SiO ₂ ), a silicon nitride film (SiN _x ), or a stacked structure thereof.

Subsequently, a single layer of an aluminum alloy, such as aluminum (Al) or aluminum-neodymium (Al-Nd), or a plurality of aluminum alloys stacked on a chromium (Cr) or molybdenum (Mo) alloy on the gate insulating layer 220. The gate electrode metal layer (not shown) is formed as a layer, and the gate electrode metal layer is etched by a photolithography process to form the gate electrode 238 at a predetermined portion corresponding to the semiconductor layer 230. Subsequently, the source region 232 and the drain region 236 are formed using the gate electrode 238 as a mask by doping a conductive impurity. An impurity doped region between the source region 232 and the drain region 236 serves as the channel region 234. However, the doping process may be performed by forming a photoresist before forming the gate electrode 238.

Next, as shown in FIG. 4C, an inorganic insulating film is deposited on the substrate 200 to form an interlayer insulating film 240 having a predetermined thickness, and the interlayer insulating film 240 and the gate insulating film 220 are photographed. Etching is performed to form contact holes 256 and 258 exposing portions of the source region 232 and the drain region 236.

Subsequently, as illustrated in FIG. 4D, a conductive material is deposited on the interlayer insulating layer 240 including the contact holes 256 and 258, and then the conductive material is patterned to form a source region 232 through the contact hole 256. A drain electrode 254 connected to the drain region 236 is formed through the source electrode 252 and the contact hole 258. In this case, molybdenum (MoW) or aluminum-neodymium (Al-Nd) may be used as the conductive material.

Next, as shown in FIG. 4E, the planarization film 250 is formed over the entire surface, and the planarization film 250 is formed over the entire surface of the substrate 200 on which the source / drain electrodes 252 and 254 are formed.

Subsequently, as illustrated in FIG. 4F, a via hole 265 exposing a portion of the source electrode 252 or the drain electrode 254, for example, a part of the drain electrode 254, is exposed to the planarization film 250. Form. This is to connect the lower electrode 270 and the drain electrode 254 to be formed in a subsequent process.

Next, as illustrated in FIG. 4G, one of the source / drain electrodes 252 and 254 may be deposited through the via hole 265 by depositing a conductive material on the planarization film 250 having a flat top surface including the via hole 265. For example, the lower electrode 270 connected to the drain electrode 254 is formed.

The lower electrode 270 is formed with a reflective film on the substrate 200 and a transparent electrode on the reflective film. The reflective film emits light from the organic film (290 shown in FIG. 3) formed in a subsequent process. ) To reflect in the opposite direction. Here, the lower electrode 270 serves as an anode electrode.

At this time, the material of the reflective film is a single metal of silver (Ag), aluminum (Al), chromium (Cr), molybdenum (Mo), tungsten (W), titanium (Ti) and thallium (Ta) and alloys thereof. As a material of the transparent electrode of the lower electrode 270, indium tin oxide (ITO) or indium zinc oxide (IZO) having a high work function may be used, and aluminum may be used in consideration of reflection efficiency and work function. Al or alloys thereof and ITO are most widely used.

Subsequently, a pixel definition layer (not shown) is formed over the entire surface. In this case, the pixel definition layer may be formed of one material selected from the group consisting of polyimide, benzocyclobutene series resin, phenol resin, and acrylate. have. The thin film as described above can be patterned by a photolithography process performed by an exposure and development process.

Next, as illustrated in FIG. 4H, the pixel definition layer is patterned by a photolithography process to form a pixel definition layer pattern 280 that exposes an emission region.

Next, as illustrated in FIG. 4I, the pixel definition layer pattern 280 is heat-treated at a glass transition temperature (Tg) for a predetermined time to reflow.

5A and 5B are scanning electron micrographs of the pixel definition layer pattern before and after the pixel definition layer pattern according to the present invention is heat-treated at Tg (glass transition temperature).

5A and 5B, when the polyimide is formed as the pixel defining layer pattern 280a and the polyimide is formed to a thickness of 1.0 μm, heat treatment is performed at Tg (glass transition temperature). The taper angle of the pixel defining layer pattern 280a is lowered. The heat treatment is a heat treatment for 50 minutes to 90 minutes at 160 ℃ Tg (glass transition temperature) of the polyimide in an N ₂ oven (oven), the taper of the pixel definition film pattern 280a in the scanning electron micrograph after the heat treatment It can be seen that the angle is lowered from 56 ° to 33.9 ° than the taper angle of the pixel definition layer pattern 280 before heat treatment.

In the present invention, the pixel definition layer pattern 280a is formed by heat-treating the polyimide at a thickness of 1.0 μm at a Tg (glass transition temperature) for 50 to 90 minutes. As the thickness increases, the taper angle of the pixel definition layer pattern 280a may be lowered by increasing the heat treatment time.

Next, the pixel definition layer pattern 280a is heat-treated at Tg (glass transition temperature), and then the temperature is raised to cure.

Subsequently, as shown in FIG. 3, an organic layer 290 including at least an organic light emitting layer is formed on the surface of the lower electrode 270 exposed by the pixel defining layer pattern 280a.

Next, an upper electrode 300 is formed on the organic layer 290 on the substrate 200. The upper electrode 300 acts as a cathode electrode and is formed of a transparent electrode, but a conductive metal having a low work function, and formed of one material selected from the group consisting of Mg, Ca, Al, Ag, and alloys thereof.

As described above, after the pixel definition layer pattern is formed, the pixel definition layer pattern is heat-treated at a glass transition temperature (Tg) for a predetermined time to reflow the pixel definition layer pattern. By lowering the taper angle of the pixel-defining film pattern of the edge portion by solving the problem, the organic film is lifted or the open defect occurs, and the organic film is lifted or the open defect occurs at the edge of the lower electrode. Since it can be prevented to improve the reliability and yield.

Although the above has been described with reference to a preferred embodiment of the present invention, those skilled in the art will be able to variously modify and change the present invention without departing from the spirit and scope of the invention as set forth in the claims below. It will be appreciated.

Claims (5)

Providing a substrate having a device; Forming a lower electrode on the substrate; Forming a pixel definition layer pattern to have an opening in an upper portion of the lower electrode; Heat treating the substrate to reflow the pixel definition layer pattern; And And forming an organic layer and an upper electrode including at least an organic light emitting layer on the lower electrode and the pixel definition layer pattern. The method of claim 1, The reflowing of the pixel definition layer pattern may include heat treatment at a Tg (glass transition temperature) of the material constituting the pixel definition layer pattern. The method of claim 1, The reflowing of the pixel definition layer pattern is performed for 50 to 90 minutes. The method of claim 1, Further comprising curing the pixel definition layer pattern above a Tg (glass transition temperature) temperature of a material constituting the pixel definition layer pattern after reflowing the pixel definition layer pattern. Method of manufacturing a light emitting display device. The method of claim 1, The pixel definition layer pattern is a polyimide manufacturing method of an organic light emitting display device.

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