KR20170077371A - Organic light emitting display and method of fabricating the same - Google Patents

Abstract

The present invention relates to an organic light emitting display device capable of simplifying a structure and capable of reducing the number of mask processes and a method of manufacturing the same, and an organic light emitting display device according to the present invention is characterized in that in an area where an anode electrode and a bank overlap, The adhesion strength between the anode electrode and the bank formed in the same mask process can be improved.

Description

TECHNICAL FIELD [0001] The present invention relates to an organic light emitting diode (OLED) display device,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic light emitting diode (OLED) display and a method of manufacturing the same, and more particularly, to an OLED display capable of simplifying a structure and reducing the number of mask processes and a method of manufacturing the same.

The image display device that realizes various information on the screen is a core technology of the information communication age and it is becoming thinner, lighter, more portable and higher performance. Accordingly, an organic light emitting display device for displaying an image by controlling the amount of light emitted from the organic light emitting layer by using a flat panel display capable of reducing weight and volume, which is a disadvantage of a cathode ray tube (CRT) This organic light emitting diode OLED is a self-luminous device having low power consumption, high response speed, high luminous efficiency, high luminance and wide viewing angle.

In order to manufacture such an OLED display device, a mask process using a photomask is performed many times. Each mask process involves associated processes such as cleaning, exposure, development, and etching. Accordingly, every time one mask process is added, there is a problem that the manufacturing time and manufacturing cost for manufacturing the organic light emitting display device are increased, the defect incidence is increased, and the manufacturing yield is lowered. Therefore, there is a need to simplify the structure and reduce the number of mask processes in order to reduce the production cost, improve the production yield and production efficiency.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and it is an object of the present invention to provide an organic light emitting display device and a method of manufacturing the same which can simplify the structure and reduce the number of mask processes.

In order to achieve the above object, the organic light emitting diode display according to the present invention includes an adhesion enhancing layer disposed on the anode electrode in a region where the anode electrode and the bank overlap with each other, so that the adhesive force between the anode electrode and the bank formed in the same mask process Can be improved.

In the present invention, the anode electrode and the bank are formed through the same mask process. Accordingly, the OLED display according to the present invention can reduce the total number of mask processes by one in comparison with the prior art, thereby improving the productivity and reducing the cost. Further, in the present invention, the adhesion strength between the anode electrode and the bank can be improved by forming the adhesion strengthening layer between the anode electrode and the banks.

1 is a cross-sectional view illustrating an organic light emitting diode display according to the present invention.
2A to 2I are cross-sectional views illustrating a method of manufacturing the organic light emitting display shown in FIG.
3A to 3D are cross-sectional views for explaining a process of forming the anode electrode, the pad upper electrode, the adhesion enhancing layer, and the bank shown in FIG. 2H.
4A and 4B are graphs showing experimental results of an OLED display device according to the present invention with or without an adhesive layer.

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

1 is a cross-sectional view of an OLED display according to the present invention.

As shown in FIG. 1, the organic light emitting diode display according to the present invention includes an active region AA and a pad region PA.

A signal pad 150 connected to a signal line of at least one of a gate line and a data line is formed in a pad region PA on the substrate 101. The signal pad 150 has a pad lower electrode 152, a pad intermediate electrode 154, and a pad upper electrode 156.

The pad lower electrode 152 is formed on the gate insulating pattern 112 with the same material as the gate electrode 106. [ The pad intermediate electrode 154 is electrically connected to the pad lower electrode 152 exposed through the first pad contact hole 158a passing through the interlayer insulating film 116. [ The pad intermediate electrode 154 is formed of the same material as the source and drain electrodes 108 and 110. The pad upper electrode 156 is electrically connected to the pad intermediate electrode 154 exposed through the second pad contact hole 158b penetrating the protection film 118. [ The pad upper electrode 156 is formed of the same material as the anode electrode 132.

A light shielding layer 102, a thin film transistor T, a storage capacitor 140, a color filter 122, a bank 138, a light emitting element 130, and an adhesive reinforcing layer (not shown) are formed in a pixel region AA on the substrate 101 146 are formed.

The thin film transistor T has a gate electrode 106, a source electrode 108, a drain electrode 110, and an active layer 114.

The gate electrode 106 is formed on the gate insulating pattern 112 in the same pattern as that of the gate electrode 106 thereof. This gate electrode 106 overlaps the channel region 114C of the active layer 114 with the gate insulating pattern 112 therebetween. The gate electrode 106 may be formed of one of Mo, Al, Cr, Au, Ti, Ni, Ne, But may be a single layer or a multilayer of these alloys, but is not limited thereto.

The source electrode 108 is connected to the source region 114S of the active layer through the source contact hole 124S penetrating the interlayer insulating film 116. [ The drain electrode 110 is connected to the drain region 114D of the active layer through the drain contact hole 124D penetrating the interlayer insulating film 116. [ The drain electrode 110 is directly connected to the anode electrode 132 through the pixel contact hole 120 formed to pass through the passivation layer 118.

The source electrode 108 and the drain electrode 110 may be formed of a metal such as Mo, Al, Cr, Au, Ti, Ni, Nd ) And copper (Cu), or an alloy thereof. However, the present invention is not limited thereto.

The active layer 114 has a source region 114S and a drain region 114D which face each other with a channel region 114C therebetween. The channel region 114C overlaps the gate electrode 106 with the gate insulating pattern 112 interposed therebetween. The source region 114S is connected to the source electrode 108 through the source contact hole 124S and the drain region 114D is connected to the drain electrode 110 through the drain contact hole 124D. Each of the source region 114S and the drain region 114D is formed of a semiconductor material into which an n-type or p-type impurity is implanted and the channel region 114C is formed of a semiconductor material into which no n-type or p-type impurity is implanted .

A buffer film 104 and a light shielding layer 102 are formed between the active layer 114 and the substrate 101. [ The light shielding layer 102 is formed on the substrate 101 so as to overlap the channel region 114C of the active layer. Since the light-shielding layer 102 absorbs or reflects light incident from the outside, the light incident on the channel region 114C can be minimized. Here, the light shielding layer 102 may be exposed through a buffer contact hole (not shown) penetrating the buffer film 104 and electrically connected to the active layer 114. In addition, the light shielding layer 102, the buffer film 104, and the active layer 114 may be formed in the same pattern at the same time. The light-shielding layer 102 is formed of an opaque metal such as Mo, Ti, Al, Cu, Cr, Co, W, Ta, or Ni.

The buffer film 104 is formed as a single layer or a multilayer structure of silicon oxide or silicon nitride on a substrate 101 formed of a plastic resin such as glass or polyimide (PI). The buffer layer 104 functions to prevent the diffusion of moisture or impurities generated in the substrate 101 or to control the transfer rate of heat during crystallization so that the crystallization of the active layer 114 can be performed well.

The storage capacitor 140 includes a storage lower electrode 142 and a storage upper electrode 144 which are overlapped with each other with an interlayer insulating film 116 interposed therebetween. At this time, the storage lower electrode 142 is formed of the same material in the same layer as the gate electrode 106 or the active layer 114. The storage upper electrode 144 is formed of the same material as the source electrode 108 in the same layer.

The color filter 122 is disposed on the protective film 118 formed to cover the storage capacitor 140 and the thin film transistors T. [ In each pixel, one of red, green, and blue color filters 122 is disposed, and these are arranged alternately. The color filter 122 may further include a white color filter 122 in addition to the red, green, and blue color filters 122. At this time, a red and / or green color filter 122 may be extended to cover the thin film transistors T on the region where the thin film transistors T are formed in the pixel region. An overcoat layer 126 for planarization is formed on the substrate 101 on which the color filters 122 are formed.

The light emitting device 130 includes an anode electrode 132 connected to the drain electrode 110 of the thin film transistor T, an organic light emitting layer 134 formed on the anode electrode 132, And a cathode electrode 136.

The anode electrode 132 is connected to the drain electrode 110 exposed through the pixel contact hole 120 passing through the protective film 118. Meanwhile, the anode electrode 132 is formed of a transparent conductive oxide (TCO) in the case of a bottom emission type OLED display.

The organic light emitting layer 134 is formed on the anode electrode 132 of the light emitting region provided by the bank 138. [ The organic light-emitting layer 134 is formed on the anode electrode 132 in the order of the hole-related layer, the light-emitting layer, and the electron-related layer in the reverse order.

The bank 138 has an inner surface IS_B in contact with the organic light emitting layer 134 and an outer surface OS_B disposed along the side surface of the anode electrode 132 so as to cover the side surface of the anode electrode 132. [ Accordingly, the bank 138 is formed so as to cover the side surface of the anode electrode 132 along the rim of the anode electrode 132 except for the light emitting region, so that the light emitting region has an open island shape. These banks 138 may be formed of an opaque material (e.g., black) to prevent optical interference between adjacent sub-pixels. In this case, the bank 138 includes a light shielding material made of at least one of a color pigment, an organic black, and a carbon.

The cathode electrode 136 is formed on the upper surface and side surfaces of the organic light emitting layer 134 and the bank 138 so as to face the anode electrode 132 with the organic light emitting layer 134 therebetween. The cathode electrode 136 is formed to include a metal material having high reflection efficiency when the organic light emitting display device is a bottom emission type organic light emitting display. For example, the cathode electrode 136 may be formed of a transparent conductive layer such as indium-tin-oxide (ITO) or indium-zinc-oxide (IZO) and a transparent conductive layer such as aluminum (Al), silver (Ag), APC (Ag; Cu), and the like are stacked.

The adhesion enhancing layer 146 has an inner surface IS_A disposed continuously with the inner surface IS_B of the bank 138 and an outer surface OS_A disposed continuously with the side surface of the anode electrode 132. [

The adhesion enhancing layer 146 is formed on the anode electrode 132 in a region where the bank 138 and the anode electrode 132 are overlapped and is formed under the bank 138 to reduce the stress difference between the electrodes 138 and 132 Thereby improving the adhesion between these members 138 and 132. That is, since the coefficient of thermal expansion of the bank 138 is larger than the coefficient of thermal expansion of the anode electrode 132, the amount of shrinkage after the firing process of the bank 138 is large, so that the anode electrode 132 has compressive stress, And have a contrast tensile stress. When the bank 138 having compressive stress is formed on the anode electrode 132 having such a tensile stress, the stress due to the compressive stress of the bank 138 is greater than the stress due to the tensile stress of the anode electrode 132, The bank 138 floats in the opposite direction to the anode electrode 132. [ In order to prevent this, in the present invention, by forming the adhesion strengthening layer 146 having tensile stress in the lower portion of the bank 138, tensile stress due to the anode electrode 132 and the adhesion strengthening layer 146, It is possible to reduce the stress difference between the compressive stresses caused by the compressive stresses and to improve the adhesive force therebetween.

The adhesion enhancing layer 146 is formed of a material different from that of the bank 138 and the anode electrode 132, respectively. When the adhesion enhancing layer 146 is formed of the same material as the bank 138, the stress caused by the compressive stress is increased, and the adhesion between the bank and the anode electrode 132 is reduced. When the adhesion enhancing layer 146 is formed of the same material as the anode electrode 132, the anode electrode 132 is also etched and damaged when the adhesion enhancing layer 146 is etched. Therefore, the adhesion enhancing layer 146 is formed of a single layer or a multi-layer structure using at least one of a metal film and an inorganic insulating film which are different from the bank 138 and the anode electrode 132, respectively. Here, the metal film includes at least one of MoTi, Al, IZO, and Mo, and the inorganic insulating film includes at least one of SiOx and SiNx.

2A to 2I are cross-sectional views illustrating a method of manufacturing the organic light emitting display shown in FIG.

Referring to FIG. 2A, a light blocking layer 102 is formed on a substrate 101.

Specifically, an opaque metal layer is formed on the substrate 101 through a deposition process. Then, the light-shielding layer 102 is formed by patterning the opaque metal layer through the photolithography process and the etching process.

Referring to FIG. 2B, a buffer layer 104 is formed on a substrate 101 on which a light shielding layer 102 is formed, and an active layer 114 is formed thereon.

The buffer film 104 and the amorphous silicon thin film are formed on the substrate 101 on which the light shielding layer 102 is formed by a method such as LPCVD (Low Pressure Chemical Vapor Deposition) or PECVD (Plasma Enhanced Chemical Vapor Deposition) . Then, the amorphous silicon thin film is crystallized to form a polysilicon thin film. Then, the active layer 114 is formed by patterning the polysilicon thin film by a photolithography process and an etching process. On the other hand, the light shielding layer 102, the buffer film 104, and the active layer 114 may be formed simultaneously using the same mask. In this case, the light shielding layer 102, the buffer film 104, and the active layer 114 are formed in the same pattern.

2C, the gate electrode 106, the storage lower electrode 142, and the pad lower electrode 152, respectively, and the gate insulating pattern 112 are formed in the same manner on the buffer film 104 on which the active layer 114 is formed Pattern.

Specifically, a gate insulating film is formed on the buffer film 104 on which the active layer 114 is formed, and a gate metal layer is formed thereon by a vapor deposition method such as sputtering. As the gate insulating film, an inorganic insulating material such as SiOx, SiNx, or the like is used. As the gate metal layer, a metal material such as Mo, Ti, Cu, AlNd, Al, Cr or an alloy thereof may be used as a single layer, or may be used as a multi-layer structure by using them. Then, the gate metal layer and the gate insulating film are simultaneously patterned through the photolithography process and the etching process, so that the gate electrode 106, the storage lower electrode 142, the pad lower electrode 152, and the gate insulating pattern 112 are the same Pattern.

The source region 114S and the drain region 114D of the active layer 114 are formed by implanting n + type or p + type impurity into the active layer 114 using the gate electrode 106 as a mask.

2D, source and drain contact holes 124S and 124D and a first pad contact hole (not shown) are formed on a substrate 101 on which a gate electrode 106, a storage lower electrode 142 and a pad lower electrode 152 are formed. An interlayer insulating film 116 having a plurality of through holes 158a is formed.

Specifically, an interlayer insulating film 116 is formed on the substrate 101 on which the gate electrode 106, the storage lower electrode 142, and the pad lower electrode 152 are formed by an evaporation method such as PECVD. Then, the interlayer insulating film 116 is patterned through the photolithography process and the etching process, so that the source and drain contact holes 124S and 124D and the first pad contact hole 158a are formed.

2E, a source electrode 108, a drain electrode 110, and a storage upper electrode (not shown) are formed on an interlayer insulating layer 116 having source and drain contact holes 124S and 124D and a first pad contact hole 158a. 144 and a pad intermediate electrode 154 are formed.

Specifically, a data metal layer is formed by an evaporation method such as sputtering on the interlayer insulating film 116 having the source and drain contact holes 124S and 124D and the first pad contact hole 158a. As the data metal layer, a metal material such as Mo, Ti, Cu, AlNd, Al, Cr or an alloy thereof may be used as a single layer, or may be used as a multi-layer structure by using them. Then, a source electrode 108, a drain electrode 110, a storage upper electrode 144, and a pad intermediate electrode 154 are formed on the interlayer insulating film 116 by patterning the data metal layer through a photolithography process and an etching process .

Referring to FIG. 2F, a protective film 118 is formed on the interlayer insulating film 116 in which the source electrode 108, the drain electrode 110, the storage upper electrode 144, and the pad intermediate electrode 154 are formed. And a blue color filter 122 are sequentially formed.

Specifically, the protective film 118 is formed on the interlayer insulating film on which the source electrode 108, the drain electrode 110, the storage upper electrode 144, and the pad intermediate electrode 154 are formed. As the protective film 118, an inorganic insulating material such as SiOx, SiNx, or the like is used. Then, a red (R) color filter 122 is formed by applying a red color layer entirely on the protective film 118 and then patterning it by a photolithography process. Then, a green color filter 122 is formed by applying a green color layer on the entire surface of the substrate 101 on which the red (R) color filter 122 is formed, and then patterning by a photolithography process. Then, the blue color layer 122 is formed by applying the blue color layer on the entire surface of the substrate 101 on which the green color filter 122 is formed and then patterning it by a photolithography process. At this time, each of the red, green, and blue color filters 122 may be formed not only in the light emitting region of each sub-pixel but also in the region where the thin film transistor T is formed.

Referring to FIG. 2G, an overcoat layer 126, a pixel contact hole 120, and a second pad contact hole 158b are formed on a substrate 101 on which a color filter 122 is formed.

Specifically, a transparent photosensitive film such as photo-acrylic is coated on the substrate 101 on which the color filter 122 is formed, and then a transparent photosensitive film is patterned using a halftone mask or a slit mask to form a transparent photosensitive film having a multi-stage structure . In this case, the multi-step structure photoresist film is formed to have a first thickness in the region corresponding to the transflective portion of the halftone mask and a second thickness in the region corresponding to the blocking portion of the halftone mask. The photosensitive insulating film is removed in a region corresponding to the transmissive portion of the halftone mask. The pixel contact hole 120 and the second pad contact hole 158b are formed by etching the transparent photoresist film and the protective film using the photoresist film as a mask. Then, by ashing the transparent photoresist film, the thickness of the photoresist film of the thin film transistor (T) region and the luminescent region becomes thin to become the overcoat layer 126, and the region of the storage capacitor 140 and the photoresist film of the pad region PA are removed.

Referring to FIG. 2H, an anode electrode 132, a pad upper electrode 156, and an adhesive layer 140 are formed on a substrate 101 on which an overcoat layer 126 and a pixel contact hole 120 and a second pad contact hole 158b are formed. The reinforcing layer 146 and the bank 138 are simultaneously formed. 4A to 4D will be specifically described below.

A transparent conductive film 132a and an adhesive strengthening material 146a are sequentially coated on the entire surface of the substrate 101 on which the overcoat layer 126 is formed as shown in FIG. Then, a photoresist film is coated on the entire surface of the adhesion enhancing material 146a, and then exposed and developed using a halftone mask or a slit mask to form a multi-layered photoresist film having different thicknesses as shown in FIG. 3B 160 are formed. The multistage structure photoresist layer 160 includes a first photoresist layer 160A having a first thickness and a second photoresist layer 160B having a second thickness that is thicker than the first thickness. The adhesion enhancing material 146a and the transparent conductive film 132a are sequentially wet-etched using the multi-step structure photoresist 160 as a mask. 3C, the anode electrode 132 and the pad upper electrode 156 are formed, and the adhesive strength layer 146 is formed on the anode electrode 132 and the pad upper electrode 156, respectively. Are formed in the same pattern. In this case, the outer surface OS_A of the adhesion enhancing layer 146 is continuously arranged with the side surface of the anode electrode 132. [

 The photoresist layer 160 is then reflowed through a curing process so that the photoresist layer 160 covers the side surfaces of the exposed anode electrode 132 and the pad upper electrode 156. Then, the first and second photoresist layers 160A and 160B are ashed so that the first photoresist layer 160A having a first thickness located on the light emitting area and the pad area PA is removed, The adhesion enhancing layer 146 located on each of the upper electrode 156 and the anode electrode 132 is exposed and the second photoresist layer 160B of the second thickness is thinned to be the bank 138. [ Then, the adhesion enhancing layer 146, which is not overlapped with the bank on the light emitting region and the pad region PA and is exposed to the outside, is removed through the etching process using the bank 138 as a mask, thereby forming the light emitting region and the pad region PA And the pad upper electrode 156 are exposed. Accordingly, the inner side IS_A of the adhesion enhancing layer 146 is continuously disposed with the inner side IS_B of the bank 138. [ On the other hand, the ashing process and the etching process of the adhesion enhancing layer 146 may be simultaneously performed through the same etching gas in the same chamber.

2I, an organic light emitting layer 134 and a cathode electrode 136 are formed on a substrate 101 on which an anode electrode 132, a pad upper electrode 156, an adhesion enhancing layer 146, and a bank 138 are formed. Respectively. The organic light emitting layer 134 is formed in the light emitting region exposed by the bank 138 and the cathode electrode 136 is formed on the substrate 101 on which the organic light emitting layer 134 is formed.

Thus, in the present invention, the anode electrode 152, the pad upper electrode 156, the adhesion enhancing layer 146, and the bank 138 are formed through the same mask process. Accordingly, the OLED display according to the present invention can reduce the total number of mask processes by one in comparison with the prior art, thereby improving the productivity and reducing the cost.

FIGS. 4A and 4B are diagrams for evaluating the reliability of the organic light emitting display according to the present invention, with or without an adhesion enhancing layer. FIG. FIG. 4A is a result of an experiment of a comparative example in which an adhesion enhancing layer is not provided between an anode electrode and a bank, and FIG. 4B is an experimental result of an embodiment having an adhesion layer between the anode electrode and the banks.

As shown in FIG. 4A, the bank of the comparative example formed on the anode electrode has a weak adhesive force between the anode electrodes, and the etching bias is increased by about 13 to 16 μm after the etching process. When the banks of this comparative example are cured, the side surfaces of the banks have taper angles of about 20 to 30 degrees, and the bottom surfaces of the banks, which form side surfaces and taper angles of the banks, have a line width of about 7 mu m to 10 mu m . As a result, it is difficult to form the bank of the comparative example in a fine pattern, and it is difficult to apply the high resolution.

On the other hand, as shown in FIG. 4B, the bank of the embodiment formed on the adhesion enhancing layer has improved adhesion to the anode electrode by the adhesion enhancing layer, so that the line width and etch bias of the bank are smaller than those of the comparative example after the etching process Loses. When the banks of this embodiment are cured, the sides of the banks have taper angles of about 60-80 degrees, and the bottom surfaces of the banks overlapping the tapered sides have a tail of a line width of about 2 mu m to 4 mu m. Accordingly, the bank of the embodiment of the present invention can be formed in a fine pattern as compared with the bank of the comparative example, and thus it is easy to apply to a high resolution.

The foregoing description is merely illustrative of the present invention, and various modifications may be made by those skilled in the art without departing from the spirit of the present invention. Accordingly, the embodiments disclosed in the specification of the present invention are not intended to limit the present invention. The scope of the present invention should be construed according to the following claims, and all the techniques within the scope of equivalents should be construed as being included in the scope of the present invention.

132: anode electrode 134: light emitting layer
136: cathode electrode 138: bank
146: Adhesion strengthening layer

Claims (9)

A light emitting element having a cathode electrode and an anode electrode facing each other with a light emitting layer interposed therebetween;
A bank disposed on the anode electrode and providing a light emitting region of the light emitting layer;
And an adhesion enhancing layer disposed on the anode electrode in a region where the anode electrode and the bank overlap each other. The method according to claim 1,
Wherein the adhesion enhancing layer is made of a material different from the anode electrode and the bank,
Wherein the adhesion enhancing layer comprises a single layer or a multilayer structure using at least one of a metal film and an inorganic insulating film. 3. The method of claim 2,
Wherein the metal film includes at least one of MoTi, Al, IZO, and Mo,
Wherein the inorganic insulating film includes at least one of SiOx and SiNx. The method according to claim 1,
The bank
An inner surface contacting the light emitting layer,
And an outer surface disposed along an edge of the anode electrode to cover the side surface of the anode electrode. 5. The method of claim 4,
The adhesive reinforcing layer
An inner surface continuously disposed with an inner surface of the bank;
And an outer side surface that is continuous with a side surface of the anode electrode. The method according to claim 1,
Wherein the thermal expansion coefficient of the bank is larger than the thermal expansion coefficient of the anode electrode. The method according to claim 1,
Wherein the adhesion enhancing layer is disposed under the bank. Forming an anode electrode, an adhesion enhancing layer and a bank sequentially stacked on a substrate;
Forming a light emitting layer in a light emitting region provided by the bank;
And forming a cathode electrode facing the anode electrode with the light emitting layer interposed therebetween,
Wherein the adhesion enhancing layer is disposed on the anode electrode in a region where the anode electrode and the bank overlap. 9. The method of claim 8,
Wherein the step of forming the anode electrode, the adhesion enhancing layer and the bank sequentially stacked on the substrate comprises:
Applying a transparent conductive film and an adhesive reinforcing material on the substrate;
Forming a photosensitive film having a multi-layered structure on the adhesive reinforcing material;
Forming the adhesion enhancing layer on the anode electrode by etching the adhesion enhancing material and the transparent conductive film using the multi-layered photoresist film as a mask;
Curing the photosensitive film of the multi-stage structure;
Forming a cushioning photosensitive layer of the cured multi-layer structure as a bank;
And etching the adhesion enhancing layer not overlapping with the bank using the bank as a mask.

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