KR20180074260A - Organic light emitting display device - Google Patents

Abstract

The present invention relates to an organic light emitting display device. An organic light emitting display device according to an embodiment of the present invention comprises a substrate in which a plurality of subpixels each having an organic light emitting device are defined; a multi-buffer layer on the substrate; a first protection member and a second protection member which are arranged on the multi-buffer layer; a first thin film transistor which is arranged on the first protection member and has an active layer, a gate electrode, a source electrode, and a drain electrode; and a second thin film transistor which is arranged on the second protection member and has an active layer, a gate electrode, a source electrode, and a drain electrode. The first protection member overlaps with the active layer of the first thin film transistor, and comes in contact with one of the source and drain electrodes of the first thin film transistor. Additionally, the second protection member overlaps with the source and drain electrodes of the second thin film transistor.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an organic light-

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an organic light emitting display, and more particularly, to an organic light emitting display capable of suppressing damage to a multi-buffer layer during contact etching.

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 device has attracted attention.

The organic light emitting device is advantageous in that it can be made thin as a self-luminous device using a thin light emitting layer between electrodes. A general organic light emitting display has a structure in which a pixel driving circuit and an organic light emitting element are formed on a substrate, and light emitted from the organic light emitting element passes through the substrate to display an image.

Since the organic light emitting display device is implemented without a separate light source device, it is easy to be implemented as a flexible display device. At this time, a flexible material such as a plastic such as polyimide (PI) is used as the substrate of the organic light emitting display device.

In a flexible organic light emitting display device using a plastic substrate, a buffer layer including a multi-buffer layer is formed between a substrate and a thin film transistor to protect the thin film transistor from impurities such as alkaline ions flowing out from the substrate.

In recent years, as flexible organic light emitting display devices have become thinner, they have reached the limit of securing an etching margin in the contact process. Accordingly, the reliability of the device is deteriorating as the etching process proceeds to the multi-buffer layer by the contact process.

Therefore, there is a need for a method for securing an optimum contact process condition that can suppress damage to the multi-buffer during contact etching or research on a new structure.

An object of the present invention is to provide an organic light emitting diode display capable of suppressing damage of a multi-buffer layer when forming a contact hole.

It is another object of the present invention to provide an organic light emitting display device capable of suppressing the reliability of the device.

Further, it is an object of the present invention to provide an organic light emitting display device in which the performance of the device can be improved.

The problems of the present invention are not limited to the above-mentioned problems, and other problems not mentioned can be clearly understood by those skilled in the art from the following description.

According to an aspect of the present invention, there is provided an organic light emitting display including a substrate having a plurality of sub-pixels each having an organic light emitting element, a multi-buffer layer on the substrate, 1 protection member and a second protection member, a first thin film transistor arranged on the first protection member and having an active layer, a gate electrode, a source electrode and a drain electrode, and a second thin film transistor arranged on the second protection member, And a second thin film transistor having a gate electrode, a source electrode, and a drain electrode, wherein the first protective member overlaps the active layer of the first thin film transistor and contacts one of the source electrode and the drain electrode of the first thin film transistor, And the second protective member overlaps the source electrode and the drain electrode of the second thin film transistor.

According to another aspect of the present invention, there is provided an OLED display including a flexible substrate having a display region and a non-display region, a multi-buffer layer disposed on the flexible substrate, A lower protective metal layer which is disposed between the multi-buffer layer and the first thin film transistor and overlaps with at least an active layer of the first thin film transistor and is in contact with one of a source electrode and a drain electrode of the first thin film transistor, A bottom shield metal (BSM), and an etch stopper disposed between the multi-buffer layer and the second thin film transistor and in contact with one of a source electrode and a drain electrode of the second thin film transistor.

The details of other embodiments are included in the detailed description and drawings.

According to the present invention, the following effects are obtained.

First, a multi-buffer layer can be prevented from being etched when a contact hole is formed by configuring a BSM in a driving transistor on one panel and an etch stopper or an etch stopper and a BSM in the switching transistor simultaneously.

Second, the damage of the multi-buffer layer can be suppressed and the reliability of the device can be prevented from lowering.

Third, a process margin can be secured at the time of contact etching using an etch stopper.

Fourth, a BSM may be formed in the driving transistor and the switching transistor to cut off the laser irradiated during the laser-releasing process, and the shift of the threshold voltage (Vth) of the transistor can be suppressed.

Fifth, by forming a BSM electrically connected to the switching transistor, the current driving capability can be improved without increasing the size of the transistor by forming the double gate electrode.

The effects according to the present invention are not limited by the contents exemplified above, and more various effects are included in the specification.

1 is a schematic plan view of an OLED display according to an embodiment of the present invention.
2 is a schematic enlarged cross-sectional view including a driving thin film transistor arranged in the SP region of FIG.
3 is a schematic enlarged cross-sectional view including a switching thin film transistor arranged in the SP region of FIG.
FIG. 4 is a schematic cross-sectional view illustrating a driving thin film transistor disposed in a sub-pixel region of an OLED display according to another embodiment of the present invention. Referring to FIG.
5 is a schematic cross-sectional view including a thin film transistor disposed in a gate driver of an OLED display according to another embodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention, and the manner of achieving them, will be apparent from and elucidated with reference to the embodiments described hereinafter in conjunction with the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Is provided to fully convey the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims.

The shapes, sizes, ratios, angles, numbers and the like disclosed in the drawings for describing the embodiments of the present invention are merely exemplary and the present invention is not limited thereto. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail. Where the terms "comprises", "having", "done", and the like are used in this specification, other portions may be added unless "only" is used. Unless the context clearly dictates otherwise, including the plural unless the context clearly dictates otherwise.

In interpreting the constituent elements, it is construed to include the error range even if there is no separate description.

In the case of a description of the positional relationship, for example, if the positional relationship between two parts is described as 'on', 'on top', 'under', and 'next to' Or " direct " is not used, one or more other portions may be located between the two portions.

It will be understood that when an element or layer is referred to as being on another element or layer, it encompasses the case where it is directly on or intervening another element or intervening another element or element.

Although the first, second, etc. are used to describe various components, these components are not limited by these terms. These terms are used only to distinguish one component from another. Therefore, the first component mentioned below may be the second component within the technical spirit of the present invention.

Like reference numerals refer to like elements throughout the specification.

The sizes and thicknesses of the individual components shown in the figures are shown for convenience of explanation and the present invention is not necessarily limited to the size and thickness of the components shown.

It is to be understood that each of the features of the various embodiments of the present invention may be combined or combined with each other partially or entirely and technically various interlocking and driving is possible as will be appreciated by those skilled in the art, It may be possible to cooperate with each other in association.

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

1 is a schematic plan view of an OLED display according to an embodiment of the present invention.

Referring to FIG. 1, the OLED display 100 may include a substrate 110, a gate driver 112, a data driver 113, and wirings 114 and 115.

The substrate 110 supports various components of the OLED display 100. A display area DA and a non-display area NA may be defined on the substrate 110. [ The display area DA may include a plurality of sub-pixels SP as a unit for realizing one color, which is an area where an image is actually displayed in the OLED display 100. The plurality of sub-pixels SP may include, for example, a red sub-pixel, a green sub-pixel, a blue sub-pixel and a white sub-pixel. The red sub-pixel, the green sub-pixel, and the blue sub-pixel form one group, thereby achieving a desired color. Each of the plurality of sub pixels SP includes an organic light emitting element composed of an anode, an organic layer, and a cathode. A more detailed description of the sub-pixel SP including the organic light emitting element will be described later with reference to FIG.

The non-display area NA can be defined as an area in which no image is displayed and an area surrounding the display area DA. In the non-display area NA, various structures for driving the plurality of sub-pixels SP arranged in the display area DA can be arranged. For example, as shown in FIG. 1, the gate driver 112, the data driver 113, the wirings 114 and 115 may be disposed in the non-display area NA of the substrate 110.

The gate driver 112 outputs a scan signal and a light emission control signal under the control of the timing controller to select a sub pixel to be charged with a data voltage through a wiring 115 such as a scan line and a light emission control signal line, have. The gate driver 112 may shift the scan signal and the emission control signal by using a shift register and sequentially supply the signals to the wire 115. [ The shift register of the gate driver 112 may be formed directly on the substrate 110 as shown in FIG. 1 by a gate-driver In Panel (GIP) method, but is not limited thereto.

The data driver 113 may convert the digital data of the input image received from the timing controller for each frame of the image displayed on the OLED display 110 into a data voltage and then supply the data voltage to the wiring 114. [ The data driver 113 may output a data voltage using a digital to analog converter (DAC) or the like that converts the digital data into a gamma compensation voltage. At this time, the wiring 114 extending from the data driver 113 and transmitting a signal to the plurality of sub-pixels SP in the display area DA is connected to the initialization voltage wiring, the emission control signal wiring, the high- Wiring, and the like.

Hereinafter, the present invention will be described with reference to FIGS. 2 to 5 for a more detailed description of a plurality of sub-pixels SP defined in the substrate 110 of the OLED display 100 according to an exemplary embodiment of the present invention.

FIG. 2 is a schematic enlarged sectional view including a driving thin film transistor disposed in the SP region of FIG. 1, and FIG. 3 is a schematic enlarged sectional view including a switching thin film transistor disposed in the SP region of FIG.

2, a sub-pixel of the OLED display 100 includes a substrate 110, a multi-buffer layer 120, a first protection member 130, an active buffer layer 135 ), A first thin film transistor TFT1 and an organic light emitting element 170. [

The substrate 110 may have a flexible characteristic. Here, a flexible characteristic can be interpreted in the same sense as a bendable, unbreakable, rollable, foldable characteristic, and the like.

For example, the substrate 110 may be made of plastic, in which case the substrate 110 may be referred to as a plastic film or a plastic substrate. For example, the substrate 110 may include one selected from the group consisting of a polyester-based polymer, a silicon-based polymer, an acrylic-based polymer, a polyolefin-based polymer, and a copolymer thereof. As a specific example, the substrate 110 may be made of polyimide (PI). Polyimide (PI) is widely used as a plastic substrate because it can be applied to a high temperature process and can be coated.

In the case where the substrate 110 is made of polyimide (PI), the manufacturing process of the organic light emitting display device is performed in a state where the support substrate made of glass is disposed under the substrate 110, The substrate can be released. Further, a back plate for supporting the substrate 110 may be disposed below the substrate 110 after the supporting substrate is released.

The multi-buffer layer 120 is disposed on the substrate 110. The multi-buffer layer 120 may comprise a single layer of silicon nitride (SiNx) or silicon oxide (SiOx), or multiple layers of silicon nitride (SiNx) or silicon oxide (SiOx). The multi-buffer layer 120 improves adhesion between the layers formed on the multi-buffer layer 120 and the substrate 110, and can block moisture, oxygen, etc. penetrating through the substrate 110.

The active buffer layer 135 may be disposed on the multi-buffer layer 120. The active buffer layer 135 protects the active layer A1 of the first thin film transistor TFT1 and functions to block various kinds of defects flowing from the substrate 110. [ The active buffer layer 135 may be made of amorphous silicon (a-Si) or the like.

The first thin film transistor TFT1 is a driving thin film transistor for driving the organic light emitting element 170 including the active layer A1, the gate electrode G1, the source electrode S1 and the drain electrode D1. The first thin film transistor TFT1 has a structure in which the active layer A1, the gate insulating layer 142, the gate electrode G1, the interlayer insulating layer 144, the source electrode S1 and the drain electrode D1 are sequentially stacked Or a top gate structure.

The active layer (A1) may be disposed on the active buffer layer (135). The active layer A1 may be made of polycrystalline silicon, in which case some regions may be doped with impurities. In addition, the active layer A1 may be formed of amorphous silicon, an organic semiconductor material, or an oxide.

The gate insulating layer 142 may be disposed on the active layer Al. The gate insulating layer 142 insulates the gate electrode G1 and the active layer A1 from each other. The gate insulating layer 142 may be formed of an insulating inorganic material such as silicon oxide (SiOx) or silicon nitride (SiNx), or may be formed of an insulating organic material or the like.

The gate electrode G1 may be disposed on the gate insulating layer 142. [ The gate electrode G1 may be formed of a metal material such as molybdenum (Mo), aluminum (Al), chrome (Cr), gold (Au), titanium (Ti), nickel (Ni), neodymium (Nd) , Or an alloy thereof. However, the present invention is not limited thereto. Further, the gate electrode G1 may be a single layer or a multilayer.

The interlayer insulating layer 144 may be disposed on the gate electrode G1. The interlayer insulating layer 144 may be formed of silicon oxide (SiOx), silicon nitride (SiNx), or multiple layers thereof, which are the same material as the gate insulating layer 142, but are not limited thereto. Meanwhile, the interlayer insulating layer 144 and the gate insulating layer 142 may include a contact hole exposing a part of the active layer Al.

The source electrode S1 and the drain electrode D1 may be disposed on the interlayer insulating layer 144. [ The source electrode S1 and the drain electrode D1 may be made of a metal such as molybdenum (Mo), aluminum (Al), chrome (Cr), gold (Au), titanium (Ti) ), Neodymium (Nd), and copper (Cu), or an alloy thereof. However, the present invention is not limited thereto. Further, the source electrode S1 and the drain electrode D1 may be a single layer or a multilayer. Each of the source electrode S1 and the drain electrode D1 is electrically connected to the active layer A1 through a contact hole.

The first protective member 130 is disposed on the multi-buffer layer 120. Further, the first protective member 130 may be disposed over the active layer A1 under the first thin film transistor TFT1. In addition, the first protective member 130 may be disposed between the multi-buffer layer 120 and the active buffer layer 135.

In the present invention, the first protective member 130 is a functional layer for performing a role as an etch stopper when forming a contact hole in the interlayer insulating layer 144 and the gate insulating layer 142 .

In this specification, the contact etching is performed by etching the interlayer insulating layer 144 and a part of the gate insulating layer 142 to electrically connect each of the source electrode S1 and the drain electrode D1 to the active layer A1 Thereby forming a contact hole.

At the time of contact etching, the end of the contact may be terminated at least at the first protective member 130 by setting the top surface of the first protective member 130. Accordingly, it is possible to prevent the contact etching from proceeding to the multi-buffer layer 120 through the first protective member 130, thereby preventing the multi-buffer layer 120 from being damaged by the etching.

The first protection member 130 may be formed of a material having a different etch selectivity from the multi-buffer layer 120 and / or the active buffer layer 135 so as to be used as an etch stopper. However, the present invention is not limited thereto. For example, the first protection member 130 may be made of a metal material. For example, the first protection member 130 may be made of the same material as the gate electrode G1 constituting the first thin film transistor TFT1. Accordingly, the first protective member 130 may be referred to as a bottom shield metal (BSM) layer.

On the other hand, since the first protection member 130 is made of a metal, the first protection member 130 may be an element that forms a capacitance with the active layer A1. At this time, if the first protective member 130 is electrically floating, a variation in capacitance may occur, and a shift amount of the threshold voltage of the first thin film transistor TFT1 may be varied, which may cause unintended visual defects For example, a luminance change). Accordingly, the first protection member 130 is electrically connected to either the source electrode S1 or the drain electrode D1 to maintain a constant capacitance. In FIG. 2, the first protective member 130 is shown in which the source electrode S1 of the first thin film transistor TFT1 is electrically connected through the contact hole. Accordingly, the same voltage as the source electrode S1 of the first thin film transistor TFT1 is applied to the first protective member 130. [

Also, when the substrate 110 is made of a plastic material, a separate supporting substrate is attached to the bottom of the substrate 110 to support the substrate 110 during the manufacturing process. At this time, a sacrificial layer is disposed between the substrate 110 and the supporting substrate. Once the fabrication process is complete, the substrate 110 and support substrate can be separated through a laser release process. The active layer A1 of the first thin film transistor TFT1 disposed on the substrate 110 may be damaged by the laser irradiated during this laser release process.

In addition, the threshold voltage Vth of the first thin film transistor TFT1 can be shifted due to the current drop phenomenon caused by the substrate 110 and the sacrifice layer. Specifically, a negative charge trap is generated in the sacrificial layer due to the laser and light emitted from the outside, and a negative charge trap is generated in the plastic material, for example, polyimide (PI) Are moved toward the sacrificial layer. Accordingly, the potential of the surface of the substrate 110 increases, and the threshold voltage Vth of the first thin film transistor TFT1 can be shifted in a positive direction. The shift of the threshold voltage (Vth) lowers the reliability of the organic light emitting diode display (100).

The first protective member 130 serves as an etch stopper as well as the first thin film transistor TFT1 that can block the laser irradiated during the laser release process as described above and can occur as the potential of the surface of the substrate 110 increases, The shift phenomenon of the threshold voltage (Vth) of the transistor can also be suppressed.

A planarizing film 150 is disposed on the first thin film transistor TFT1. The planarizing film 150 is an insulating layer for protecting the first thin film transistor TFT1 and planarizing the upper portion of the first thin film transistor TFT1. The planarization layer 150 includes a contact hole for electrically connecting the first thin film transistor TFT1 to the anode 171 of the organic light emitting diode 170. [ Specifically, the planarization film 150 includes a contact hole exposing one of the source electrode S1 and the drain electrode D1 of the first thin film transistor TFT1. The planarizing layer 150 may be formed of an organic insulating material. The planarization layer 150 may be formed of a single layer, or may have a double or multi-layer structure.

A passivation layer (not shown) for protecting the source electrode S1 and the drain electrode D1 may be further disposed on the source electrode S1 and the drain electrode D1 under the planarization layer 150. [ For example, the passivation layer is made of an inorganic material such as silicon oxide and silicon nitride, and may be composed of a single layer or a plurality of layers. The passivation layer may be formed with contact holes exposing the source electrode S1 or the drain electrode D1 through selective removal.

The organic light emitting device 170 is disposed on the planarizing film 150. The organic light emitting device 170 is driven by the first thin film transistor TFT1 and includes an anode 171 and a cathode 175 facing each other and an organic light emitting layer 173 interposed therebetween. The light emitting region of the organic light emitting element 170 can be defined by the bank 160. [

The organic light emitting device 170 may be configured to emit light in any of red, green, and blue (RGB) light, or may be configured to emit white light. When the organic light emitting diode 170 emits white light, the OLED display 100 may further include a color filter.

The anode 171 is electrically connected to the first thin film transistor TFT1. Specifically, the anode 171 may be connected to either the source electrode S1 or the drain electrode D1 of the first thin film transistor TFT1 through the contact hole formed in the planarization film 150. [ In Fig. 2, an example of the anode 171 electrically connected to the source electrode S1 of the first thin film transistor TFT1 is shown. In this case, a video signal for displaying a video signal is applied to the anode 171 through the source electrode S1.

The anode 171 is made of a conductive material having a high work function because holes must be supplied to the organic light emitting layer 173. For example, the anode 171 may be formed of a transparent conductive oxide (TCO) such as indium tin oxide (ITO). When the organic light emitting diode display 100 is a top emission organic light emitting display, the anode 171 may be a transparent conductive layer including a reflective layer having a high reflectivity at the bottom, but the present invention is not limited thereto . The anode 171 is arranged on the contact hole and a part of the planarization film 150 in a pixel-by-pixel spaced manner.

The organic light emitting layer 173 is disposed on the anode 171. The organic light emitting layer 173 may be formed of a phosphorescent or fluorescent material, and may further include a hole injection layer, a hole transport layer, an electron transport layer, and an electron injection layer, if necessary. The organic light emitting layer 173 may include a material capable of emitting light of a specific color. For example, the organic light emitting layer 173 may include a light emitting material capable of emitting light of any one of red, green, and blue light. However, without being limited thereto, the organic light emitting layer 173 may include a light emitting material capable of emitting light of a different color.

The cathode 175 is arranged to face the anode 171 with the organic light emitting layer 173 therebetween. The cathode 175 supplies electrons to the organic light emitting layer 173. When the OLED display 100 is a top emission type OLED display, the cathode 175 may be formed of a transparent conductive layer or may be formed of a very thin metal material, but the present invention is not limited thereto. For example, the cathode 175 may be made of a metallic material having a low work function such as a metal alloy such as MgAg, a metal alloy including Yb (ytterbium), or the like.

The bank 160 is disposed on the planarization film 150 in the remaining region except the light emitting region in the display region. That is, the bank 160 is disposed so as to cover only a part of the anode 171 so as to expose a part of the anode 171, and an area corresponding to a part of the anode 171 exposed by the bank 160 serves as a light- Can be defined. The bank 160 may be formed of an inorganic insulating material such as silicon oxide, silicon nitride, or an organic insulating material such as BCB, acrylic resin, or imide resin.

An encapsulant (not shown) is disposed on the cathode 175 of the organic light emitting device 170. The encapsulation unit is configured to protect the organic light emitting device 170, which is vulnerable to moisture, from exposure to moisture. For example, the sealing portion may include, but is not limited to, a structure in which an inorganic layer and an organic layer are alternately stacked, or a structure in which an inorganic layer / an organic layer / an inorganic layer are stacked.

On the other hand, the sub-pixel of the OLED display 100 includes the first thin film transistor TFT1 shown in FIG. 2 and the second thin film transistor TFT2 shown in FIG.

3, a sub-pixel of the OLED display 100 includes a substrate 110, a multi-buffer layer 120, a second protection member 180, an active buffer layer 135, a second thin film transistor TFT2, And an organic light emitting element 170. At this time, only the structure of the second protection member 180 and the second thin film transistor TFT2 are different from each other, and the remaining structure is the same as that of FIG. 2, and therefore only the differences will be described.

The second thin film transistor TFT2 is a switching thin film transistor for driving the organic light emitting element 170 including the active layer A2, the gate electrode G2, the source electrode S2 and the drain electrode D2, Gate structure. And the second thin film transistor TFT2 may be disposed on the second protective member 180. [

The second protective member 180 is disposed on the multi-buffer layer 120 and overlaps the source electrode S2 and the drain electrode D2 of the second thin film transistor TFT2. Specifically, the second protective member 180 may include a first portion 181 overlapping the source electrode S2 and a second portion 182 overlapping the drain electrode D2. That is, the second protection member 180 is electrically connected to the source electrode S2 and the drain electrode D2 of the gate electrode G2, the source electrode S2 and the drain electrode D2 of the second thin film transistor TFT2 except for the gate electrode G2, And overlaps the electrode D2.

In general, in an OLED display, a switching transistor is designed without an arrangement of a lower protective metal layer below the active layer. However, for all the transistors disposed on one panel at the mask reduction level, The contact holes are formed through the contact etching in a lump.

Accordingly, in the case of the drive transistor in which the lower protective metal layer is disposed under the active layer during contact etching, the multi-buffer layer is not damaged, but in the case of the switching transistor not using the lower protective metal layer, Which adversely affects the reliability of the apparatus.

In the present invention, the second protection member 180 is introduced as an etch stopper under the active layer of the switching transistor to prevent etching damage of the multi-buffer layer due to the contact etching described above.

The second protective member 180 may be formed of a material having a different etch selectivity from the multi-buffer layer 120 and / or the active buffer layer 135 so as to be used as an etch stopper. However, the present invention is not limited thereto. For example, the second protection member 180 may be made of a metal material. When the second protection member 180 is made of a metal material, it is electrically connected to the source electrode S2 and the drain electrode D2 so that the capacitance is kept constant. Thus, the same voltage as the source electrode S2 and the drain electrode D2 of the second thin film transistor TFT2 is applied to the second protective member 180. [

Meanwhile, the first portion 181 and the second portion 182 of the second protection member 180 may be disposed apart from each other as shown in FIG. 3, but may be integrally formed.

As described above, when the second protective member 180 is formed below the active layer A2 of the second thin film transistor TFT2, the first portion 181 and the second portion 182 of the second protective member 180, Etching of the multi-buffer layer 120 can be prevented since the contact etching is terminated in the step 182, thereby reducing the reliability of the device.

In the OLED display 100 according to an exemplary embodiment of the present invention, the BSM 130 is formed in the first thin film transistor TFT1, thereby ensuring a process margin at the time of contact etching to prevent damage to the multi-buffer layer 120 It is possible to cut off the laser irradiated during the laser-releasing process and also to suppress the shift phenomenon of the threshold voltage (Vth) of the first thin film transistor TFT1, which may occur as the potential of the surface of the substrate 110 increases, have.

However, not all BSMs are required for all transistors in the design, and the performance of the transistors may be deteriorated by using the lower BSM.

However, if the BSM is not used for all the transistors, the active buffer layer 135 and the multi-buffer layer 120 of the second thin film transistor TFT2 are damaged at the time of forming the contact holes in the first thin film transistor TFT1, The reliability of the apparatus can be deteriorated because it can not block moisture or oxygen penetrating through the substrate 110 and various kinds of defects introduced from the substrate 110.

Therefore, in the OLED display 100 according to the embodiment of the present invention, the second protective member 180 is formed under the active layer A2 of the second thin film transistor TFT2 to form the multi- 120 can be prevented from being damaged.

FIG. 4 is a schematic cross-sectional view illustrating a driving thin film transistor disposed in a sub-pixel region of an OLED display according to another embodiment of the present invention. Referring to FIG. 4 only differs from that of the organic light emitting diode display 200, and the remaining components are the same as those in FIG. The first thin film transistor TFT1 of FIG. 4 is a driving thin film transistor for driving the organic light emitting element 170, and has a top gate structure.

5 is a schematic cross-sectional view including a thin film transistor disposed in a gate driver of an OLED display according to another embodiment of the present invention.

5, the gate driver of the OLED display 100 according to another embodiment of the present invention is disposed in a non-display region and includes a substrate 110, a multi-buffer layer 120, a third protection member 280, An active buffer layer 135, a second thin film transistor TFT2 and an organic light emitting element 170. [ At this time, only the connection structure of the third protection member 280, the third protection member 280 and the second thin film transistor TFT2 is different, and the remaining components are the same as those of FIGS. 2 and 3, Explain only the differences.

The second thin film transistor TFT2 is a switching thin film transistor for driving the organic light emitting element 170 and has a top gate structure.

The third protective member 280 is disposed on the multi-buffer layer 120 and overlaps the gate electrode G2, the source electrode S2, and the drain electrode D2 of the second thin film transistor TFT2. Specifically, the third protection member 280 includes a first portion 281 overlapping with the source electrode S2, a second portion 282 overlapping with the drain electrode D2, and a second portion 282 overlapped with the gate electrode G2. 3 portion 283 of the second embodiment.

The first portion 281 and the second portion 282 of the third protective member 280 are used as an etch stopper when forming a contact hole in the interlayer insulating layer 144 and the gate insulating layer 142 , Thereby ensuring the process margin and preventing the etching damage of the multi-buffer layer 120.

Each of the first portion 281 and the second portion 282 of the third protective member 280 is electrically connected to the source electrode S2 and the drain electrode D2 to keep the capacitance constant. The same voltage as the source electrode S2 and the drain electrode D2 of the second thin film transistor TFT2 is applied to the first portion 281 and the second portion 282 of the third protective member 280. [

The third portion 283 of the third protective member 280 may be electrically connected to the second thin film transistor TFT2. Specifically, the third portion 283 is electrically connected to the gate electrode G2 of the second thin film transistor TFT2 to apply the same voltage as the gate electrode G2. At this time, the third portion 283 of the third protective member 280 may function as an assist gate electrode to form a double gate electrode. Thereby, an additional channel region can be provided on the surface of the active layer A2 of the second thin film transistor TFT2.

Therefore, the mobility of the second thin film transistor TFT2 can be increased without substantially increasing the size of the second thin film transistor TFT2. That is, the current driving capability of the second thin film transistor TFT2 can be improved.

Further, by configuring the third portion 283 of the third protective member 280 in the second thin film transistor TFT2, the laser irradiated during the laser releasing process can be blocked, and the potential of the surface of the substrate 110 is increased The shift phenomenon of the threshold voltage (Vth) of the second thin film transistor (TFT2) that can occur can be suppressed.

On the other hand, the first portion 281 and the second portion 282 of the third protective member 280 may be disposed apart from each other as shown in FIG. 5, but may be integrally formed.

In the organic light emitting diode display 200 according to another embodiment of the present invention, the BSM 130 is formed in the first thin film transistor TFT1 to secure a process margin at the time of contact etching, thereby preventing damage to the multi buffer layer 120 It is possible to cut off the laser irradiated during the laser-releasing process and also to suppress the shift phenomenon of the threshold voltage (Vth) of the first thin film transistor TFT1, which may occur as the potential of the surface of the substrate 110 increases, have.

In addition, by configuring the BSM 283 in addition to the etch stoppers 281 and 282 in the second thin film transistor TFT2, etch damage of the multi-buffer layer 120 due to the contact etching can be prevented, The current driving capability of the second thin film transistor TFT2 can be improved and the laser irradiated during the laser releasing process can be cut off and the second thin film transistor TFT2, which can occur as the potential of the surface of the substrate 110 increases, The shift of the threshold voltage (Vth) of the transistor Q1 can also be suppressed.

Particularly, in both of the first thin film transistor (TFT1) which is a driving transistor arranged in the display region and the second thin film transistor (TFT2) which is a switching transistor arranged in the gate driving portion of the non-display region, The protective member 130 and the third protective member 280 are formed to prevent the active buffer layer 135 and the multi-buffer layer 120 of the second thin film transistor TFT2 from being damaged at the time of forming the contact holes, Deterioration can be prevented.

An exemplary embodiment of the present invention can be described as follows.

According to an aspect of the present invention, there is provided an organic light emitting diode (OLED) display device including a substrate having a plurality of subpixels each having an organic light emitting device, a multi-buffer layer on the substrate, A first thin film transistor disposed on the first protective member and disposed on the first protective member, the first thin film transistor having an active layer, a gate electrode, a source electrode, and a drain electrode, And a second thin film transistor having an active layer, a gate electrode, a source electrode and a drain electrode, wherein the first protective member overlaps the active layer of the first thin film transistor, and the source electrode and the drain electrode of the first thin film transistor And the second protective member overlaps the source electrode and the drain electrode of the second thin film transistor.

According to another aspect of the present invention, the second protection member includes a first portion contacting the source electrode of the second thin film transistor and a second portion contacting the drain electrode of the second thin film transistor.

According to another aspect of the present invention, the second protective member includes a first portion contacting the source electrode of the second thin film transistor and a second portion contacting the drain electrode of the second thin film transistor.

According to still another aspect of the present invention, the second protective member overlaps only the source electrode and the drain electrode among the gate electrode, the source electrode, and the drain electrode of the second thin film transistor.

According to another aspect of the present invention, the first thin film transistor is a driving thin film transistor for driving the organic light emitting element, and the second thin film transistor is a switching thin film transistor for driving the organic light emitting element.

According to another aspect of the present invention, the second protective member further includes a third portion overlapping the gate electrode of the second thin film transistor, and the third portion is electrically connected to the second thin film transistor .

According to another aspect of the present invention, a first thin film transistor is a driving thin film transistor for driving the organic light emitting element, and the second thin film transistor is disposed in a gate driving portion.

According to another aspect of the present invention, the first portion and the second portion are integrally formed.

According to another aspect of the present invention, the gate electrode of the first thin film transistor is disposed on the active layer of the first thin film transistor, and the gate electrode of the second thin film transistor is disposed on the active layer of the second thin film transistor .

According to another aspect of the present invention, the substrate is formed of a plastic material.

According to another aspect of the present invention, there is further provided an active buffer layer covering the multi-buffer layer, the first protection member, and the second protection member.

According to another aspect of the present invention, there is provided an OLED display including a flexible substrate having a display region and a non-display region, a multi-buffer layer disposed on the flexible substrate, A lower protective metal layer which is disposed between the multi-buffer layer and the first thin film transistor and overlaps with at least an active layer of the first thin film transistor and is in contact with one of a source electrode and a drain electrode of the first thin film transistor, And an etch stopper disposed between the multi-buffer layer and the second thin film transistor and in contact with one of the source electrode and the drain electrode of the second thin film transistor.

According to another aspect of the present invention, the first thin film transistor and the second thin film transistor are thin film transistors of a top gate structure.

According to still another aspect of the present invention, the etch stopper overlaps the second thin film transistor in a region excluding the gate electrode of the second thin film transistor.

According to another aspect of the present invention, the first thin film transistor is a driving thin film transistor for driving the organic light emitting element disposed in the display region, and the second thin film transistor is a driving thin film transistor for driving the organic light emitting element And is a switching thin film transistor.

According to still another aspect of the present invention, there is provided a display device, further comprising a double gate electrode which overlaps the gate electrode of the second thin film transistor and is electrically connected to the second thin film transistor in the non-display region.

According to another aspect of the present invention, a first thin film transistor is a driving thin film transistor for driving an organic light emitting element disposed in a display region, and a second thin film transistor is a thin film transistor constituting a gate driving portion disposed in a non- .

Although the embodiments of the present invention have been described in detail with reference to the accompanying drawings, it is to be understood that the present invention is not limited to those precise embodiments and various changes and modifications may be made without departing from the scope of the present invention. . Therefore, the embodiments disclosed in the present invention are intended to illustrate rather than limit the scope of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. Therefore, it should be understood that the above-described embodiments are illustrative in all aspects and not restrictive. The scope of protection of the present invention should be construed according to the following claims, and all technical ideas within the scope of equivalents should be construed as falling within the scope of the present invention.

100, 200: organic light emitting display
110: substrate
112: Gate driver
113:
114, 115: Wiring
120: multi-buffer layer
130: first protection member
135: active buffer layer
142: Gate insulating layer
144: interlayer insulating layer
150: planarization film
160: Bank
170: Organic light emitting device
171: anode
173: Organic light emitting layer
175: Cathode
180: second protection member
181, 281: first part
182, 282: the second part
280: third protection member
283: third part
DA: Display area
NA: non-display area
SP: sub-pixel
TFT1: first thin film transistor
TFT2: second thin film transistor
A1, A2: active layer
G1, G2: gate electrode
S1, S2: source electrode
D1, D2: drain electrode

Claims (16)

A substrate on which a plurality of sub-pixels each having an organic light emitting element are defined;
A multi-buffer layer on the substrate;
A first protective member and a second protective member disposed on the multi-buffer layer;
A first thin film transistor disposed on the first protective member and having an active layer, a gate electrode, a source electrode, and a drain electrode; And
And a second thin film transistor disposed on the second protective member and including an active layer, a gate electrode, a source electrode, and a drain electrode,
Wherein the first protective member overlaps the active layer of the first thin film transistor and contacts one of the source electrode and the drain electrode of the first thin film transistor,
And the second protective member overlaps the source electrode and the drain electrode of the second thin film transistor. The method according to claim 1,
Wherein the second protective member includes a first portion in contact with a source electrode of the second thin film transistor and a second portion in contact with a drain electrode of the second thin film transistor. 3. The method of claim 2,
And the second protective member overlaps only the source electrode and the drain electrode among the gate electrode, the source electrode, and the drain electrode of the second thin film transistor. The method of claim 3,
The first thin film transistor is a driving thin film transistor for driving the organic light emitting element,
And the second thin film transistor is a switching thin film transistor for driving the organic light emitting element. 3. The method of claim 2,
Wherein the second protective member further includes a third portion overlapping a gate electrode of the second thin film transistor,
And the third portion is electrically connected to the second thin film transistor. 6. The method of claim 5,
The first thin film transistor is a driving thin film transistor for driving the organic light emitting element,
And the second thin film transistor is disposed in the gate driver. 3. The method of claim 2,
Wherein the first portion and the second portion are integrally formed. The method according to claim 1,
Wherein a gate electrode of the first thin film transistor is disposed on an active layer of the first thin film transistor,
And a gate electrode of the second thin film transistor is disposed on an active layer of the second thin film transistor. The method according to claim 1,
Wherein the substrate is made of a plastic material. The method according to claim 1,
And an active buffer layer covering the multi-buffer layer, the first protective member, and the second protective member. A flexible substrate having a display region and a non-display region;
A multi-buffer layer disposed on the flexible substrate;
A first thin film transistor and a second thin film transistor arranged on the multi-buffer layer;
A lower protective metal layer disposed between the multi-buffer layer and the first thin film transistor and overlapping at least an active layer of the first thin film transistor and in contact with one of a source electrode and a drain electrode of the first thin film transistor; And
And an etch stopper disposed between the multi-buffer layer and the second thin film transistor and in contact with one of a source electrode and a drain electrode of the second thin film transistor. 12. The method of claim 11,
Wherein the first thin film transistor and the second thin film transistor are thin film transistors of a top gate structure. 12. The method of claim 11,
Wherein the etch stopper overlaps the second thin film transistor in a region excluding the gate electrode of the second thin film transistor. 14. The method of claim 13,
Wherein the first thin film transistor is a driving thin film transistor for driving the organic light emitting element arranged in the display region,
And the second thin film transistor is a switching thin film transistor for driving the organic light emitting element disposed in the display region. 12. The method of claim 11,
And a double gate electrode overlapping a gate electrode of the second thin film transistor and electrically connected to the second thin film transistor in the non-display region. 16. The method of claim 15,
Wherein the first thin film transistor is a driving thin film transistor for driving the organic light emitting element arranged in the display region,
And the second thin film transistor is a thin film transistor constituting a gate driver arranged in the non-display region.

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