KR102596361B1 - Thin film transistor and display apparatus comprising the same - Google Patents

Abstract

The present invention relates to a thin film transistor and a display device including the same. The thin film transistor according to an embodiment of the present invention is disposed on a substrate and includes an active layer made of an oxide semiconductor material, a gate insulating layer on the active layer, and a gate insulating layer. A gate electrode overlapping the active layer with an interlayer in between, an interlayer insulating layer on the gate electrode, a source electrode and a drain electrode electrically connected to the active layer through a contact hole formed in the interlayer insulating layer, and spaced apart from each other on the interlayer insulating layer; and an oxide barrier layer electrically connected to one of the source electrode and the drain electrode and disposed on the interlayer insulating layer to overlap the gate electrode. Accordingly, the performance of the thin film transistor can be prevented from being reduced by blocking hydrogen from flowing into the active layer made of an oxide semiconductor material.

Description

Thin film transistor and display device including same {THIN FILM TRANSISTOR AND DISPLAY APPARATUS COMPRISING THE SAME}

This specification relates to a thin film transistor and a display device including the same, and more specifically, to a thin film transistor and a display device that can prevent performance degradation due to hydrogen.

Recently, as we entered the full-fledged information age, the field of displays that visually express electrical information signals has developed rapidly, and in response to this, various display devices (Display Apparatus) with excellent performance such as thinness, weight, and low power consumption have been developed. is being developed. Specific examples of such display devices include electroluminescence displays such as liquid crystal displays (LCDs), organic light emitting displays (OLEDs), and quantum dot light emitting displays (QLEDs).

An electroluminescent display device includes a display area for displaying an image and a non-display area disposed adjacent to the display area. And, the pixel area includes a pixel circuit and a light emitting element. A plurality of thin film transistors are located in the pixel circuit to drive light emitting elements arranged in a plurality of pixels.

Thin film transistors can be classified according to the material that makes up the active layer. Among them, low temperature poly-silicon (LTPS) thin film transistors and oxide thin film transistors are the most widely used. Meanwhile, the technology development of electroluminescent display devices in which LTPS thin film transistors and oxide thin film transistors are formed on the same substrate is being actively developed.

Meanwhile, the inventor of the present specification recognized that the operating characteristics of a pixel can be improved by using a multi-type thin film transistor in which a plurality of thin film transistors are formed of different semiconductors in a display device.

LTPS thin film transistors use polysilicon materials with high mobility (more than 100 cm2/Vs), so they have low energy consumption and excellent reliability. On the other hand, oxide thin film transistors use a material with a larger band gap as the active layer compared to LTPS thin film transistors. Because of this, the oxide thin film transistor has a low off-current, has a short on time, and can maintain a long off time. Although not limited thereto, LTPS thin film transistors can be used in driving thin film transistors, and oxide thin film transistors can be used in switching thin film transistors.

Meanwhile, electroluminescent display devices such as organic light emitting display devices and quantum dot light emitting display devices include various organic material layers formed on thin film transistors. For example, a protective layer to protect the thin film transistor, a planarization layer to planarize the upper part of the thin film transistor, or an encapsulation layer to protect the thin film transistor and the display device, etc. may be disposed. This organic material layer can generate hydrogen at high temperatures during the manufacturing process. In addition, as the display device is driven, hydrogen and hydrogen ions may be generated in various organic material layers.

Hydrogen and hydrogen ions generated inside the display device may diffuse and affect the electrodes and active layers constituting the thin film transistor, reducing brightness or causing pixel defects. In particular, in the case of oxide thin film transistors, there is a problem that when hydrogen diffuses into the oxide semiconductor material constituting the active layer, carriers are generated and the threshold voltage (Vth) may change.

Accordingly, the inventors of the present specification recognized the above-mentioned problems and developed technology to prevent defects in thin film transistors caused by hydrogen.

The problem to be solved by the present invention is to provide a thin film transistor and a display device that can block hydrogen, which can affect the thin film transistor, from diffusing into the gate electrode or active layer.

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

In order to solve the above-described problem, a thin film transistor according to an embodiment of the present invention is disposed on a substrate and includes an active layer made of an oxide semiconductor material, a gate insulating layer on the active layer, and an active layer with the gate insulating layer in between. Overlapping gate electrodes, an interlayer insulating layer on the gate electrode, a source electrode and a drain electrode electrically connected to the active layer through a contact hole formed in the interlayer insulating layer, and spaced apart from each other on the interlayer insulating layer, and a source electrode and a drain electrode. It is electrically connected to any one of the electrodes and includes an oxide barrier layer disposed on the interlayer insulating layer to overlap the gate electrode. Accordingly, the performance of the thin film transistor can be prevented from being reduced by blocking hydrogen from flowing into the active layer made of an oxide semiconductor material.

In order to solve the problems described above, a display device according to an embodiment of the present invention includes a first thin film transistor including a low-temperature polysilicon material, a second thin film transistor including an oxide semiconductor material, a first thin film transistor, and a second thin film transistor. 2 disposed on a thin film transistor, and includes an organic light-emitting device including an anode, an organic light-emitting layer, and a cathode, and an encapsulation portion disposed on the organic light-emitting device, wherein hydrogen generated in the encapsulation portion is transferred to the second thin film. In order to block inflow into the transistor, an oxide barrier layer made of oxide is included between the gate electrode and the active layer of the second thin film transistor and the encapsulation part.

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

The present invention can prevent a decrease in performance of the thin film transistor by disposing an oxide barrier layer between the thin film transistor and the organic light emitting device, thereby blocking hydrogen from flowing in from the organic layer on the top of the thin film transistor.

In addition, the present invention can suppress the inflow of hydrogen ions by applying a positive potential to the oxide barrier layer connected to the source electrode or drain electrode, using a repulsive force with hydrogen ions.

In addition, the present invention can solve problems of performance degradation and threshold voltage changes of switching transistors containing oxide semiconductor materials in display devices containing multi-type thin film transistors containing different semiconductor materials.

The effects according to the present invention are not limited to the details exemplified above, and further various effects are included within the present invention.

1A to 1C are cross-sectional views showing a display device according to an embodiment of the present specification.
Figure 2 is a cross-sectional view showing a display device according to another embodiment of the present specification.
Figure 3 is a cross-sectional view showing a display device according to another embodiment of the present specification.
Figure 4 is a cross-sectional view showing a display device according to another embodiment of the present specification.

The advantages and features of the present invention and methods for achieving them will become clear by referring to the embodiments described in detail below along with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below and will be implemented in various different forms, but the present embodiments only serve to complete the disclosure of the present invention, and are not limited to the embodiments disclosed below, and are known to those skilled in the art in the technical field to which the present invention pertains. It is provided to fully inform those who have the scope of the invention, and the present invention is only defined by the scope of the claims.

The shape, size, ratio, angle, number, etc. disclosed in the drawings for explaining embodiments of the present invention are illustrative and the present invention is not limited to the matters shown. Like reference numerals refer to like elements throughout the specification. Additionally, in describing the present invention, if it is determined that a detailed description of related known technologies may unnecessarily obscure the gist of the present invention, the detailed description will be omitted. When 'comprises', 'has', 'consists of', etc. mentioned in the present invention are used, other parts may be added unless 'only' is used. When a component is expressed in the singular, the plural is included unless specifically stated otherwise.

When interpreting a component, it is interpreted to include the margin of error even if there is no separate explicit description.

In the case of a description of a positional relationship, for example, if the positional relationship of two parts is described as 'on top', 'on the top', 'on the bottom', 'next to', etc., 'immediately' Alternatively, there may be one or more other parts placed between the two parts, unless 'directly' is used.

When an element or layer is referred to as “on” another element or layer, it includes instances where the other layer or other element is directly on top of or interposed between the other elements.

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

Like reference numerals refer to like elements throughout the specification.

The size and thickness of each component shown in the drawings are shown for convenience of explanation, and the present invention is not necessarily limited to the size and thickness of the components shown.

Each feature of the various embodiments of the present invention can be combined or combined with each other, partially or entirely, and various technological interconnections and operations are possible, and each embodiment can be implemented independently of each other or together in a related relationship. It may be possible.

Hereinafter, the present invention will be described with reference to the drawings.

1A to 1C are cross-sectional views showing a display device according to an embodiment of the present specification.

Referring to FIG. 1A, the display device 100 according to an embodiment of the present specification includes a substrate 110, a buffer layer 111, an oxide thin film transistor 120, a gate insulating layer 112, an interlayer insulating layer 113, It includes an oxide barrier layer 130, a protective layer 114, a planarization layer 115, a bank 140, an organic light emitting device 150, and an encapsulation portion 160.

The substrate 110 supports various components of the display device 100. The substrate 110 may be made of glass or a plastic material with flexibility. For example, the substrate 110 may be made of polyimide (PI). When the substrate 110 is made of polyimide (PI), the display device manufacturing process proceeds with a support substrate made of glass placed below the substrate 110, and after the display device manufacturing process is completed, the support substrate is released ( can be released. Additionally, after the support substrate is released, a back plate for supporting the substrate 110 may be placed under the substrate 110.

The buffer layer 111 is formed on the entire surface of the substrate 110. The buffer layer 111 may improve the adhesion between the layers formed on the buffer layer 111 and the substrate 110 and block alkaline components leaking from the substrate 110. The buffer layer 111 may be made of a single layer or multiple layers of silicon nitride (SiNx) or silicon oxide (SiOx). The buffer layer 111 is not an essential component and may be omitted depending on the type and material of the substrate 110, the structure and type of the thin film transistor, etc.

The oxide thin film transistor 120 is disposed on the buffer layer 111. The oxide thin film transistor 120 may include an active layer 121, a gate electrode 124, a source electrode 122, and a drain electrode 123. The active layer 121 of the oxide thin film transistor 120 may be disposed on the buffer layer 111.

The active layer 121 is made of an oxide semiconductor material. Oxide semiconductor materials have a larger band gap than silicon materials, so electrons cannot cross the band gap in the off state. That is, the oxide semiconductor material has a low off-current, which is the leakage current between the source and drain of the transistor in the off state. Accordingly, a thin film transistor including an active layer made of an oxide semiconductor material may be suitable as a switching thin film transistor that maintains a short on time and a long off time, but is not limited thereto. Depending on the characteristics of the display device, it may be applied as a driving thin film transistor. Additionally, the oxide semiconductor material has a small off-current, so the size of the auxiliary capacitance can be reduced, making it suitable for high-resolution display devices. The active layer 121 may be made of a metal oxide, for example, various metal oxides such as indium-gallium-zinc-oxide (IGZO). The active layer 121 of the oxide thin film transistor 120 has been described as being formed based on the IGZO layer, assuming that it is made of IGZO among various metal oxides, but is not limited to this and is not limited to IGZO, but ZnO (Zinc Oxide), IZO (indium -zinc-oxide), indium-gallium-tin-oxide (IGTO), or indium-gallium-oxide (IGO).

The active layer 121 may be formed by depositing a metal oxide on the buffer layer 111, performing a heat treatment process for stabilization, and then patterning the metal oxide.

An insulating material layer and a metal material layer may be sequentially formed on the entire surface of the substrate 110 including the active layer 121, and a photoresist pattern may be formed on the metal material layer. The insulating material layer can be formed using the PECVD method, and the metal material layer can be formed using sputtering.

The gate electrode 124 can be formed by wet etching the metal material layer using the photoresist pattern as a mask. The wet etching solution for etching the metal material layer consists of molybdenum (Mo), copper (Cu), titanium (Ti), aluminum (Al), chromium (Cr), gold (Au), and nickel (Ni). , materials that selectively etch neodymium (Nd) or their alloys and do not etch the insulating material layer can be used.

The gate insulating layer 112 can be formed by dry etching the insulating material layer using the photoresist pattern and the gate electrode 124 as a mask. Through a dry etching process, the insulating material layer may be etched to form a gate insulating layer 112 pattern on the active layer 121. Thereafter, the active layer 121 exposed by the patterned gate insulating layer 112 may be made into a conductor through a dry etching process.

An active layer including a non-conductive channel region 121a corresponding to the area where the gate electrode 124 is formed, and a source region 121b and a drain region 121c that are conductive at both ends of the active layer 121, respectively. (121) can be formed.

The resistance of the source region 121b and the drain region 121c of the conductive active layer 121 is lowered, so that the device performance of the oxide thin film transistor 120 can be improved, and accordingly, according to the embodiments of the present specification The effect of improving the reliability of the display device 100 can be obtained.

The channel region 121a of the active layer 121 may be disposed to overlap the gate electrode 124. The source region 121b and drain region 121c of the active layer 121 may be disposed on both sides of the channel region 121a. The gate insulating layer 112 may be disposed between the gate electrode 124 and the active layer 121. The gate insulating layer 112 may be disposed to overlap the gate electrode 124 and the channel region 121a of the active layer 121.

By etching the insulating material layer and the metal material layer using the photoresist pattern PR as a mask, the gate insulating layer 112 and the gate electrode 124 may be formed in the same pattern. The gate insulating layer 112 may be disposed on the active layer 121. The gate insulating layer 112 may be composed of a single layer or multiple layers of silicon nitride (SiNx) or silicon oxide (SiOx). The gate insulating layer 112 may be patterned to overlap the active layer 121.

The gate electrode 124 is disposed on the gate insulating layer 112. The gate electrode 124 is made of any one of molybdenum (Mo), copper (Cu), titanium (Ti), aluminum (Al), chromium (Cr), gold (Au), nickel (Ni), and neodymium (Nd). It can be formed as a single layer or multiple layers made of alloy. The gate electrode 124 may be patterned to overlap the active layer 121 and the gate insulating layer 112. The gate electrode 124 may be patterned to overlap the channel region 121a of the active layer 121. Additionally, the gate insulating layer 112 may be patterned to overlap the channel region 121a of the active layer 121. Accordingly, the gate electrode 124 and the gate insulating layer 112 may overlap the channel region 121a of the active layer 121.

The interlayer insulating layer 113 is disposed on the buffer layer 111, the active layer 121, and the gate electrode 124. The interlayer insulating layer 113 may be composed of a single layer or multiple layers of silicon nitride (SiNx) or silicon oxide (SiOx). A contact hole may be formed in the interlayer insulating layer 113 to expose the source region 121b and drain region 121c of the active layer 121 of the oxide thin film transistor 120.

A source electrode 122 and a drain electrode 123 are formed on the interlayer insulating layer 113. The source electrode 122 and the drain electrode 123 may be connected to the active layer 121 through a contact hole formed in the interlayer insulating layer 113. For example, the source electrode 122 and the drain electrode 123 are electrically connected to the source region 121b and drain region 121c of the active layer 121, respectively, through a contact hole formed in the interlayer insulating layer 113. can be connected The source electrode 122 and the drain electrode 123 are made of a conductive metal material. For example, the source electrode 122 and the drain electrode 123 are made of molybdenum (Mo), copper (Cu), titanium (Ti), aluminum (Al), chromium (Cr), gold (Au), nickel (Ni), It may be formed as a single layer or multiple layers made of neodymium (Nd) or an alloy thereof. For example, the source electrode 122 and the drain electrode 123 may have a three-layer structure of titanium (Ti)/aluminum (Al)/titanium (Ti), but are not limited thereto.

The oxide barrier layer 130 is disposed on the interlayer insulating layer 113. The oxide barrier layer 130 is arranged to overlap the gate electrode 124 on the interlayer insulating layer 113, so that hydrogen generated at the top of the oxide thin film transistor 120 diffuses to the gate electrode 124 or the active layer 121. block it from happening. The oxide barrier layer 130 may overlap a portion of the gate electrode 124, but may overlap to completely cover the top of the gate electrode 124 to block hydrogen.

Referring to FIG. 1B, a planarization layer 115 is disposed on the oxide thin film transistor 120 to planarize the upper part of the oxide thin film transistor 120. Additionally, an encapsulation unit 160 is disposed on the organic light emitting device 150 disposed on the planarization layer 115 to protect the organic light emitting device 150 from moisture or oxygen. At this time, the planarization layer 115 and the encapsulation portion 160 may be made of an organic material layer, and hydrogen (H) may be generated due to high temperature during the manufacturing process. Additionally, in the case of the organic material layer, hydrogen or hydrogen ions may be generated as the display device is driven. Hydrogen or hydrogen ions generated in the organic material layer diffuse downward and adversely affect the gate electrode 124 and the active layer 121 constituting the oxide thin film transistor 120. In particular, as hydrogen (H) flows into the active layer 121, carriers are generated in the active layer 121 and the threshold voltage (Vth) may change.

Referring to FIG. 1B, hydrogen (H) formed on the top of the oxide thin film transistor 120 is physically blocked by the oxide barrier layer 130 and does not flow into the gate electrode 124 and the active layer 121. Accordingly, the oxide thin film transistor 120 is protected from hydrogen (H) and can maintain transistor performance.

Meanwhile, the oxide barrier layer 130 is disposed to be electrically connected to either the source electrode 122 or the drain electrode 123 on the interlayer insulating layer 113. Referring to FIG. 1A, the oxide barrier layer 130 is arranged to be in direct contact with the drain electrode 123, but is arranged to be spaced apart from the source electrode 122 without contacting the source electrode 122. At this time, the oxide barrier layer 130 may have a structure that is in contact with the drain electrode 123 so as to be electrically connected. For example, in Figure 1a, the left end of the oxide barrier layer 130 is disposed below the right end of the drain electrode 123, so that portions of the oxide barrier layer 130 and the drain electrode 123 overlap and contact each other vertically. Although shown as being done, it is not limited thereto, and one side of the oxide barrier layer 130 may be in contact with one side of the drain electrode 123.

The oxide barrier layer 130 is electrically connected to either the source electrode 122 or the drain electrode 123, so that it can receive the same potential as the source electrode 122 or the drain electrode 123.

Referring to FIG. 1C, as the display device is continuously driven, the planarization layer 115 and the encapsulation portion 160 containing organic materials may deteriorate and generate hydrogen ions (H ⁺ ). Since the hydrogen ion (H ⁺ ) has a positive charge, when a negative potential is applied to the gate electrode 124, the hydrogen ion (H ⁺ ) is transferred to the gate electrode due to the attractive force between the hydrogen ion (H + ) and the gate electrode ¹²⁴ . It can be captured on the surface of (124). When hydrogen ions (H ⁺ ) are collected in the gate electrode 124, voids and a porous layer may be formed around the gate electrode 124. Additionally, hydrogen ions (H ⁺ ) trapped around the gate electrode 124 may form hydrogen molecules and diffuse to the lower active layer 121. That is, when a negative potential is applied to the gate electrode 124 of the oxide thin film transistor 120, the gate electrode 124 serves to attract hydrogen ions (H ⁺ ) formed inside the display device 100.

At this time, the oxide barrier layer 130 is in direct contact with the drain electrode 123 and therefore receives the same potential as the connected drain electrode 123. Generally, a positive potential is applied to the drain electrode 123 and the source electrode 122, so the oxide barrier layer 130 has a positive potential like the drain electrode 123. When the oxide barrier layer 130 has a positive potential, a repulsive force occurs between the hydrogen ions (H ⁺ ) formed on the top of the oxide thin film transistor 120 and the oxide barrier layer 130. Accordingly, hydrogen ions (H ⁺ ) do not diffuse toward the gate electrode 124 and the active layer 121 of the oxide thin film transistor 120, but diffuse upward due to a repulsive force with the oxide barrier layer 130. Accordingly, the oxide thin film transistor 120 can be protected from hydrogen ions (H ⁺ ).

The oxide barrier layer 130 may be made of metal oxide. For example, the oxide barrier layer 130 may be made of metal oxide. For example, the oxide barrier layer 130 may include indium-gallium-zinc-oxide (IGZO), zinc oxide (ZnO), indium-zinc-oxide (IZO), indium-gallium-tin-oxide (IGTO), and IGO ( indium-gallium-oxide) or a combination thereof. The oxide barrier layer 130 made of metal oxide can block hydrogen generated at the top of the oxide thin film transistor 120 from flowing into the gate electrode 124 or the active layer 121.

Additionally, the oxide barrier layer 130 may include the same material as the active layer 121 of the oxide thin film transistor 120. For example, when the active layer 121 is made of IGZO, the oxide barrier layer 130 may also be made of IGZO. When the oxide barrier layer 130 and the active layer 121 are made of the same material, there is an advantage that the process for forming the active layer 121 and the process for forming the oxide barrier layer 130 can be shared. That is, the same materials and devices used in the process of forming the active layer 121 can be used in the process of forming the oxide barrier layer 130, thereby saving process time and cost during manufacturing. In addition, since the oxide barrier layer 130 and the active layer 121 are made of the same material, the same potential can be applied to the oxide barrier layer 130 and the active layer 121, which results in the oxide barrier layer ( 130) can implement the same bias environment as the active layer 121.

The oxide barrier layer 130 may have a thickness of 200Å to 600Å, but is not limited thereto. By forming the thickness of the oxide barrier layer 130 to be 200Å to 600Å, hydrogen can be effectively blocked and manufacturing of the oxide barrier layer 130 can be facilitated.

The protective layer 114 is disposed on the source electrode 122, the drain electrode 123, the oxide barrier layer 130, and the interlayer insulating layer 113. As shown in FIG. 1A, a contact hole may be formed in the protective layer 114 to expose the drain electrode 123, but is not limited thereto. The protective layer 114 may be an inorganic layer to protect the upper part of the oxide thin film transistor 120. For example, it may be composed of a single layer of silicon nitride (SiNx) or silicon oxide (SiOx) or multiple layers thereof. The protective layer 114 can suppress hydrogen diffusing from the top of the oxide thin film transistor 120. The protective layer 114 may be omitted depending on the characteristics of the display device 100 or the structure and characteristics of the thin film transistor according to the embodiment of the present specification.

The planarization layer 115 is disposed on the protective layer 114. A contact hole may be formed in the planarization layer 115 to expose the drain electrode 123 of the oxide thin film transistor 120, but is not limited thereto. The planarization layer 115 may be an organic material layer for planarizing the top of the oxide thin film transistor 120. For example, the planarization layer 115 is made of organic resins such as acryl resin, epoxy resin, phenolic resin, polyamide resin, and polyimide resin. It can be formed from materials.

The organic light emitting device 150 is disposed on the planarization layer 115. The organic light emitting device 150 includes a first electrode 151 connected to the oxide thin film transistor 120, an organic light emitting layer 152 disposed on the first electrode 151, and a second electrode disposed on the organic light emitting layer 152. Includes (153).

The first electrode 151 may be disposed on the planarization layer 115 and electrically connected to the drain electrode 123 of the oxide thin film transistor 120 through a contact hole formed in the planarization layer 115 and the protective layer 117. there is.

When the display device 100 according to an embodiment of the present specification is a top emission display device, the first electrode 151 may be an anode electrode. When the display device 100 is a bottom emission display device, the first electrode 151 disposed on the planarization layer 115 may be a cathode electrode.

When the first electrode 151 is an anode, the first electrode 151 may be made of a conductive material with a high work function in order to supply holes to the organic light emitting layer 152. The first electrode 151 is, for example, a transparent conductive material such as indium tin oxide (ITO), indium zinc oxide (IZO), indium tin zinc oxide (ITZO), etc. It can be done with When the display device 100 is a top emitting display device, the first electrode 151 has a reflective layer for reflecting light emitted from the organic light emitting layer 152 toward the second electrode 153 and a hole in the organic light emitting layer 152. It may include a transparent conductive layer for supply. However, the first electrode 151 may be defined as including only a transparent conductive layer and the reflective layer may be a separate component from the first electrode 151.

In Figure 1, the first electrode 151 is shown as being electrically connected to the drain electrode 123 of the oxide semiconductor oxide thin film transistor 120 through a contact hole, but the first electrode 151 is shown as being electrically connected to the drain electrode 123 of the oxide semiconductor oxide thin film transistor 120. The first electrode 151 may be configured to be electrically connected to the source electrode 124 of the oxide semiconductor oxide thin film transistor 120 through a contact hole.

The organic light-emitting layer 152 is a layer for emitting light of a specific color and may include one of a red light-emitting layer, a green light-emitting layer, a blue light-emitting layer, and a white light-emitting layer. Additionally, the organic light-emitting layer 152 may further include various layers such as a hole transport layer, a hole injection layer, an electron injection layer, and an electron transport layer. In FIG. 1A, the organic emission layer 152 is shown as being formed as one layer over the entire display area, but it may also be patterned.

The second electrode 153 is disposed on the organic light emitting layer 152. When the display device 100 is a top emitting display device, the second electrode 153 may be a cathode electrode. When the second electrode 153 is a cathode, the second electrode 153 is made of indium tin oxide (ITO), indium zinc oxide (IZO), or indium tin zinc oxide (Indium Tin Zinc Oxide). It may be made of a transparent conductive oxide of the ITZO (ITZO), zinc oxide (ZnO), and tin oxide (Tin oxide (TO) series) or a ytterbium (Yb) alloy. Alternatively, the second electrode 153 may be made of a metal material.

Referring to FIG. 1A, a bank 140 is disposed on the first electrode 151 and the overcoating layer 115. The bank 140 may define a light-emitting area by covering a portion of the first electrode 151 of the organic light-emitting device 150. Bank 140 may be made of organic material. For example, the bank 140 may be made of polyimide, acryl, or benzocyclobutene (BCB)-based resin, but is not limited thereto.

The encapsulation portion 160 is disposed on the organic light emitting device 150 to protect the organic light emitting device 150 from moisture or oxygen. The encapsulation portion 160 includes a first encapsulation layer 161, a second encapsulation layer 162, and a third encapsulation layer 163. The first encapsulation layer 161 and the third encapsulation layer 163 are inorganic insulating layers and may be made of one or more of silicon nitride (SiNx), silicon oxide (SiOx), or silicon oxynitride (SiON). It is not limited to this. The second encapsulation layer 161 is an organic insulating layer and may be formed of polymer. The second encapsulation layer 161 is also called a particle covering layer (PCL) and serves to cover foreign substances. For example, with foreign matter attached to the surface of the first encapsulation layer 161, the third encapsulation layer 163 made of an inorganic insulating material is disposed on the first encapsulation layer 161 without the second encapsulation layer 161. In this case, since the third encapsulation layer 163 does not have a high adhesion to the foreign matter attached to the surface of the first encapsulation layer 161, a gap may form around the foreign matter, and the third encapsulation layer 163 may form a gap due to the formation of the gap. It may peel off. Therefore, by disposing the second encapsulation layer 162 made of an organic material between the first encapsulation layer 161 and the third encapsulation layer 163, the third encapsulation layer 163 is peeled off to cover the foreign matter and the surrounding area. You can prevent it from happening.

Additionally, a capping layer may be disposed between the sealing portion 160 and the second electrode 153. The capping layer covers the organic light emitting device 150 to prevent the inflow of oxygen and moisture from the outside, and can serve to improve the efficiency of light passing through the second electrode 153, and the encapsulation portion 160. The adhesion of the cathode 153 can be improved.

The display device according to an embodiment of the present specification is electrically connected to the source electrode or the drain electrode and disposes an oxide barrier layer made of metal oxide on the interlayer insulating layer to overlap the gate electrode, thereby reducing the hydrogen generated inside the display device. Alternatively, hydrogen ions can be blocked from diffusing into the oxide thin film transistor.

Specifically, oxide thin film transistors including an active layer made of an oxide semiconductor material suffer from performance degradation due to hydrogen. Hydrogen formed from organic materials constituting the planarization layer and the encapsulation layer disposed on the thin film transistor may flow into the active layer and increase the deviation of the threshold voltage (or threshold voltage) of the thin film transistor. Accordingly, by disposing an oxide barrier layer made of metal oxide on the gate electrode and the active layer, it is possible to physically block hydrogen penetration. Additionally, by connecting the oxide barrier layer to the source electrode or the drain electrode and applying a positive potential, diffusion of hydrogen ions to the lower part of the oxide barrier layer due to repulsive force with the oxide barrier layer can be prevented. Accordingly, the display device according to an embodiment of the present specification can prevent hydrogen, which may affect the oxide thin film transistor, from diffusing into the gate electrode or active layer, and minimize performance degradation of the device due to driving.

Figure 2 is a cross-sectional view showing a display device according to another embodiment of the present specification. Since the display device 200 of FIG. 2 is different from the display device 100 of FIG. 1 only in the oxide barrier layer 230 and other configurations are substantially the same, duplicate description will be omitted.

Referring to FIG. 2 , the oxide barrier layer 230 of the display device 200 according to another embodiment of the present invention is arranged to cover not only the top but also the side of the gate electrode 124 on the interlayer insulating layer 113.

The interlayer insulating layer 113 may be disposed on the buffer layer 111, the active layer 121, and the gate electrode 124. At this time, the interlayer insulating layer 113 may be disposed conformally along the buffer layer 111, the active layer 121, the gate insulating layer 112, and the gate electrode 124. The interlayer insulating layer 113 may contact the top surface of the buffer layer 111, the side and top surface of the active layer 121, the side surface of the gate insulating layer 112, and the side and top surface of the gate electrode 124.

The interlayer insulating layer 113 is disposed to surround the gate insulating layer 112 and the gate electrode 124, and forms a step in the area where the gate insulating layer 112 and the gate electrode 124 are disposed. The interlayer insulating layer 113 is formed of an inorganic material made of silicon nitride (SiNx) or silicon oxide (SiOx). During the formation of the interlayer insulating layer 113, there is a step around the gate insulating layer 112 and the gate electrode 124. Cracks or voids (G) may occur in the area. In addition, cracks or voids (G) may occur in the interlayer insulating layer 113 disposed in the step area due to deterioration of elements resulting from driving the display device 200 and pores formed around the thin film transistor. Cracks or voids (G) may provide a path through which hydrogen or hydrogen ions generated inside the display device 200 move. Accordingly, hydrogen generated at the top of the oxide thin film transistor 220 can quickly move to the gate electrode 124 and the active layer 121 along the crack or gap (G) formed in the interlayer insulating layer 113. Because of this, a problem may occur in which the performance of the oxide thin film transistor 220 rapidly deteriorates.

Referring to FIG. 2, the oxide barrier layer 230 is arranged to cover the step area of the interlayer insulating layer 113. That is, unlike the structure in which the oxide barrier layer 130 in FIG. 1 is arranged to cover only the top of the gate electrode 124, the oxide barrier layer 230 in FIG. 2 is arranged to cover the side surfaces of the gate electrode 124. . Because of this, the oxide barrier layer 230 is disposed to contact the surface of the interlayer insulating layer 113 where the crack or gap (G) is formed, and can prevent the crack or gap (G) from being exposed to the outside.

Accordingly, the oxide barrier layer 230 can block hydrogen from moving through the side of the crack or gap (G) formed in the step area of the interlayer insulating layer 113.

Figure 3 is a cross-sectional view showing a display device according to another embodiment of the present specification. The display device 300 of FIG. 3 is different from the display device 200 of FIG. 2 only in the oxide thin film transistor 320 and the oxide barrier layer 330, and other configurations are substantially the same, so redundant description is omitted. Do this.

Referring to FIG. 3 , the oxide barrier layer 330 of the display device 300 according to another embodiment of the present invention is disposed to be electrically connected to the source electrode 322 rather than the drain electrode 323. Specifically, the oxide barrier layer 330 is arranged to directly contact the source electrode 322, and is arranged to be spaced apart from the drain electrode 323 without contacting the drain electrode 323. For example, in Figure 3, the left end of the oxide barrier layer 330 is disposed below the right end of the source electrode 322, so that the oxide barrier layer 330 and the source electrode 322 partially overlap and contact each other vertically. It is shown as doing so, but is not limited thereto.

The oxide barrier layer 330 may be electrically applied to the same potential as the source electrode 322 . Generally, a positive potential is applied to the source electrode 322, so the oxide barrier layer 330 has a positive potential like the source electrode 322. When the oxide barrier layer 30 has a positive potential, a repulsive force occurs between the hydrogen ions formed at the top of the oxide thin film transistor 320 and the oxide barrier layer 330, and the hydrogen ions are generated at the gate of the oxide thin film transistor 320. It does not diffuse in the direction of the electrode 124 and the active layer 121, but diffuses in the opposite direction due to the repulsive force. For this reason, the display device 300 according to another embodiment of the present invention can protect the oxide thin film transistor 320 from hydrogen ions using the oxide barrier layer 330.

Figure 4 is a cross-sectional view showing a display device according to another embodiment of the present specification. 4 shows a display device including a multi-type thin film transistor consisting of a plurality of thin film transistors containing different semiconductor materials. For example, the display device of FIG. 4 is an organic light emitting display device including an LTPS thin film transistor and an oxide thin film transistor.

Referring to FIG. 4, the display device 400 according to an embodiment of the present specification includes a substrate 110, a buffer layer 111, a first thin film transistor 470, a second thin film transistor 420, and a first gate insulator. Layer 412, first interlayer insulating layer 413, separation insulating layer 414, second gate insulating layer 415, second interlayer insulating layer 416, oxide barrier layer 430, protective layer 417 ), a planarization layer 418, a connection electrode 480, a bank 140, an organic light emitting device 150, and an encapsulation portion 160.

The display device 400 of FIG. 4 differs from the display device 100 of FIG. 1 in that it includes a plurality of thin film transistors, but includes a substrate 110, a buffer layer 111, a bank 140, and an organic thin film transistor. The light emitting device 150 and the encapsulation unit 160 are substantially the same. Accordingly, redundant description will be omitted for substantially the same configurations, excluding added and changed configurations.

Referring to FIG. 4 , the first thin film transistor 470 may be disposed on the buffer layer 111 . The first thin film transistor 470 may include a first active layer 471, a first gate electrode 474, a first source electrode 472, and a first drain electrode 473. The first active layer 471 of the first thin film transistor 470 may be disposed on the buffer layer 111. The first thin film transistor 470 is an LTPS thin film transistor including an active layer made of low temperature polysilicon (LTPS).

The first active layer 471 includes low temperature polysilicon (LTPS). Low-temperature polysilicon materials have high mobility (over 100㎠/Vs), low energy consumption and excellent reliability, so they can be applied to gate drivers and/or multiplexers (MUX) for driving devices that drive thin film transistors for display devices. However, it is not limited to this. Polysilicon is formed by depositing an amorphous silicon (a-Si) material on the buffer layer 111, performing a dehydrogenation process and a crystallization process, and the first active layer 471 is formed by patterning the polysilicon. You can. The first active layer 471 includes the first channel region 471a, where a channel is formed when the first thin film transistor 470 is driven, the first source region 471b on both sides of the first channel region 471a, and the first It may include a drain area 471c. The first source region 471b refers to a portion of the first active layer 471 connected to the first source electrode 472, and the first drain region 471c refers to a portion of the first active layer 471 connected to the first drain electrode 473. It refers to a portion of the layer 471. The first channel region 471a, the first source region 471b, and the first drain region 471c may be formed by ion doping (impurity doping) of the first active layer 471. The first source region 471b and the first drain region 471c may be created by ion-doping a polysilicon material, and the first channel region 471a may refer to a portion left as a polysilicon material without ion doping. there is.

A first gate insulating layer 412 may be disposed on the first active layer 471 of the first thin film transistor 470. The first gate insulating layer 412 may be composed of a single layer or multiple layers of silicon nitride (SiNx) or silicon oxide (SiOx). The first gate insulating layer 412 includes the first source electrode 472 and the first drain electrode 473 of the first thin film transistor 470, respectively, of the first active layer 471 of the first thin film transistor 470. Contact holes may be formed to connect to each of the first source region 471b and the first drain region 471c.

The first gate electrode 474 of the first thin film transistor 470 may be disposed on the first gate insulating layer 412. Since the first gate electrode 474 is substantially the same as the gate electrode 124 of FIG. 1, duplicate description will be omitted.

A first interlayer insulating layer 413 may be disposed on the first gate insulating layer 412 and the first gate electrode 474. Since the first interlayer insulating layer 413 is substantially the same as the interlayer insulating layer 113 of FIG. 1, duplicate description will be omitted.

A first source electrode 472 and a first drain electrode 473 may be formed on the first interlayer insulating layer 413. The first source electrode 472 and the first drain electrode 473 may be connected to the first active layer 471 through a contact hole formed in the first interlayer insulating layer 413 and the first gate insulating layer 412. . For example, the first source electrode 472 and the first drain electrode 473 are connected to the first active layer 471 through contact holes formed in the first interlayer insulating layer 413 and the first gate insulating layer 412. ) may be electrically connected to the first source region 471b and the first drain region 471c, respectively. Since the constituent materials of the first source electrode 472 and the first drain electrode 473 are substantially the same as those of the source electrode 122 and the drain electrode 123 of FIG. 1, duplicate description will be omitted.

A separation insulating layer 414 is disposed on the first interlayer insulating layer 413, the first source electrode 472, and the first drain electrode 473. The isolation insulating layer 414 serves to separate the second thin film transistor 420 disposed on the isolation insulating layer 414 and the first thin film transistor 470 disposed below the isolation insulating layer 414. For example, the isolation insulating layer 414 is disposed on the first source electrode 472 and the first drain electrode 473 of the first thin film transistor 470, and the second thin film transistor 420 is disposed on the first source electrode 472 and the first drain electrode 473. can be placed. A contact hole may be formed in the separation insulating layer 414 to expose at least a portion of the first source electrode 472 and the first drain electrode 473. The isolation insulating layer 414 may be composed of a single layer of silicon nitride (SiNx) or silicon oxide (SiOx) or multiple layers thereof.

The second active layer 421 of the second thin film transistor 420 may be disposed on the isolation insulating layer 114. The second thin film transistor 420 may include a second active layer 421, a second gate electrode 424, a second source electrode 422, and a second drain electrode 423. The second thin film transistor 420 is an oxide thin film transistor including an active layer made of an oxide semiconductor. That is, since the second thin film transistor 420 of FIG. 4 is substantially the same as the oxide thin film transistor 120 described in FIG. 1, duplicate description will be omitted.

A second gate insulating layer 415 may be disposed on the second active layer 421. Since the second gate insulating layer 415 is substantially the same as the gate insulating layer 412 of FIG. 1, duplicate description will be omitted.

The second gate electrode 424 of the second thin film transistor 420 may be disposed on the second gate insulating layer 415. Since the second gate electrode 424 is substantially the same as the gate electrode 124 of FIG. 1, duplicate description will be omitted.

A second interlayer insulating layer 416 may be disposed on the second gate insulating layer 415 and the second gate electrode 424. Since the second interlayer insulating layer 416 is substantially the same as the interlayer insulating layer 113 of FIG. 1, duplicate description will be omitted.

A second source electrode 422, a second drain electrode 423, an oxide barrier layer 430, and a connection electrode 480 may be disposed on the second interlayer insulating layer 416. Since the second source electrode 422 and the second drain electrode 423 are substantially the same as the source electrode 122 and the drain electrode 123 of FIG. 1, duplicate description will be omitted.

The oxide barrier layer 430 is disposed on the second interlayer insulating layer 416. The oxide barrier layer 430 is arranged to overlap the second gate electrode 424 on the second interlayer insulating layer 416, so that hydrogen generated on the top of the second thin film transistor 420 flows to the second gate electrode 424 or It blocks diffusion into the second active layer 421. The oxide barrier layer 430 may overlap a portion of the second gate electrode 424, but may overlap to completely cover the top of the second gate electrode 424 to block hydrogen. Since the oxide barrier layer 430 is substantially the same as the oxide barrier layer 130 of FIG. 1, duplicate description will be omitted.

The connection electrode 480 may be electrically connected to the first drain electrode 473 through a contact hole formed in the separation insulating layer 414 and the second interlayer insulating layer 416, but is not limited thereto. For example, the connection electrode 480 may be electrically connected to the first drain electrode 473 through a contact hole formed in the separation insulating layer 414 and the second interlayer insulating layer 416. In addition, when forming the connection electrode 480 electrically connected to the first drain electrode 473 through the contact hole formed in the separation insulating layer 414 and the second interlayer insulating layer 416, the separation insulating layer 414 ) and a first auxiliary source electrode electrically connected to the first source electrode 472 through a contact hole formed in the second interlayer insulating layer 416 may be further formed.

The connection electrode 480, the second source electrode 422, and the second drain electrode 423 may be formed through the same process. Also, the connection electrode 480, the second source electrode 422, and the second drain electrode 423 may be formed of the same material.

The display device 400 according to another embodiment of the present invention includes a first thin film transistor 470 including a low-temperature polysilicon material and a second thin film transistor 420 including an oxide semiconductor material. The second thin film transistor 420 including an oxide semiconductor material is electrically connected to the second source electrode 422 or the second drain electrode 423, and has a second interlayer insulating layer to overlap the second gate electrode 424. It is disposed on (416) and includes an oxide barrier layer (430) made of metal oxide. The oxide barrier layer 430 allows hydrogen or hydrogen ions generated in the planarization layer 418 and the encapsulation portion 160 disposed on the second thin film transistor 420 to pass through the second gate electrode 424 of the second thin film transistor 420. ) and diffusion to the second active layer 421.

In particular, the second thin film transistor 420 containing an oxide semiconductor material can be used as a switching thin film transistor. A switching thin film transistor has a short on time and a long off time, and during the off time, the gate electrode of the switching thin film transistor has a negative potential. When the gate electrode has a negative potential, positively charged hydrogen ions (H ⁺ ) quickly move to the gate electrode due to electrical attraction with the gate electrode. Ultimately, many hydrogen ions and hydrogen atoms may diffuse into the active layer, changing the electrical properties of the active layer and significantly reducing performance.

However, a display device according to another embodiment of the present invention arranges an oxide barrier layer connected to the source electrode or drain electrode of the second thin film transistor used as a switching thin film transistor on the gate electrode and the active layer, so that hydrogen or hydrogen ions Infiltration can be suppressed.

A display device according to various embodiments of the present invention may be described as follows.

A thin film transistor according to an embodiment of the present invention is disposed on a substrate and includes an active layer made of an oxide semiconductor material, a gate insulating layer on the active layer, a gate electrode overlapping the active layer with the gate insulating layer in between, and an interlayer on the gate electrode. It is electrically connected to the active layer through a contact hole formed in the insulating layer and the interlayer insulating layer, and is electrically connected to one of the source electrode and the drain electrode arranged to be spaced apart from each other on the interlayer insulating layer, and the source electrode and the drain electrode, and an oxide barrier layer disposed on the interlayer insulating layer to overlap the gate electrode.

According to another feature of the present invention, the oxide barrier layer may include the same material as the active layer.

According to another feature of the present invention, the active layer and the oxide barrier layer include indium-gallium-zinc-oxide (IGZO), zinc oxide (ZnO), indium-zinc-oxide (IZO), and indium-gallium-tin- (IGTO). oxide), IGO (indium-gallium-oxide), or a combination thereof.

According to another feature of the present invention, potentials opposite to each other may be applied to the gate electrode and the oxide barrier layer.

According to another feature of the present invention, a negative potential may be applied to the gate electrode, and a positive potential may be applied to the oxide barrier layer.

According to another feature of the present invention, the oxide barrier layer may be in direct contact with the source electrode or the drain electrode.

According to another feature of the present invention, the thickness of the oxide barrier layer may be 200Å to 600Å.

According to another feature of the present invention, the oxide barrier layer can completely cover the top of the gate electrode.

According to another feature of the present invention, the interlayer insulating layer is disposed to cover the active layer, the gate insulating layer, and the gate electrode, the interlayer insulating layer forms a step in the area where the gate electrode is disposed, and the oxide barrier layer is an interlayer insulating layer. It can be arranged to cover the level difference in the floor.

According to another feature of the present invention, the interlayer insulating layer includes a gap formed in a portion adjacent to the gate electrode, and the oxide barrier layer may be disposed to contact the surface of the interlayer insulating layer to cover the gap.

A display device according to an embodiment of the present invention is disposed on a first thin film transistor including a low-temperature polysilicon material, a second thin film transistor including an oxide semiconductor material, the first thin film transistor and the second thin film transistor, and an anode. , an organic light-emitting device including an organic light-emitting layer and a cathode, and an encapsulation portion disposed on the organic light-emitting device, wherein the second thin film transistor blocks hydrogen generated in the encapsulation portion from flowing into the second thin film transistor, It includes an oxide barrier layer made of oxide between the gate electrode and the active layer of the second thin film transistor and the encapsulation part.

According to another feature of the present invention, the first thin film transistor includes a first active layer made of a low-temperature polysilicon material, a first gate insulating layer on the first active layer, and disposed on the first gate insulating layer and overlapping with the first active layer. It includes a first gate electrode, a first interlayer insulating layer on the gate electrode, and a first source electrode and a first drain electrode disposed on the first interlayer insulating layer and connected to the first active layer, and the second thin film transistor is made of oxide. a second active layer made of a semiconductor material, a second gate insulating layer on the second active layer, a second gate electrode disposed on the second gate insulating layer and overlapping the second active layer, a second interlayer insulating layer on the gate electrode, and a second source electrode and a second drain electrode disposed on the second interlayer insulating layer and connected to the second active layer.

According to another feature of the present invention, the oxide barrier layer is disposed on the second interlayer insulating layer to overlap the second gate electrode and may be in direct contact with the second source electrode and the second drain electrode.

According to another feature of the present invention, the second active layer and the oxide barrier layer include indium-gallium-zinc-oxide (IGZO), indium-gallium-zinc-oxide (ZnO), indium-zinc-oxide (IZO), and indium-gallium-oxide (IGTO). It may be made of tin-oxide), IGO (indium-gallium-oxide), or a combination thereof.

According to another feature of the present invention, the oxide barrier layer may be disposed to cover the top and sides of the second gate electrode.

According to another feature of the present invention, the first thin film transistor may be a driving thin film transistor, and the second thin film transistor may be a switching thin film transistor.

Although embodiments of the present invention have been described in more detail with reference to the accompanying drawings, the present invention is not necessarily limited to these embodiments, and various modifications may be made without departing from the technical spirit of the present invention. . Accordingly, the embodiments disclosed in the present invention are not intended to limit the technical idea of the present invention but are for illustrative purposes, and the scope of the technical idea of the present invention is not limited by these embodiments. Therefore, the embodiments described above should be understood in all respects as illustrative and not restrictive. The scope of protection of the present invention should be interpreted in accordance with the claims below, and all technical ideas within the equivalent scope should be construed as being included in the scope of rights of the present invention.

100, 200, 300, 400: display device
110: substrate
111: buffer layer
112: Gate insulating layer
113: Interlayer insulation layer
114: protective layer
115: Flattening layer
120, 220, 320: oxide thin film transistor,
121: active layer
122, 322: source electrode
123, 323: drain electrode
124: Gate electrode
130, 230, 330: Oxide barrier layer
140: bank
150: Organic light emitting device
151: anode
152: Organic light emitting layer
153: cathode
160: Encapsulation part
161: first encapsulation layer
162: Second encapsulation layer
163: Third encapsulation layer

Claims (16)

An active layer disposed on a substrate and made of an oxide semiconductor material;
a gate insulating layer on the active layer;
a gate electrode overlapping the active layer with the gate insulating layer interposed therebetween;
an interlayer insulating layer on the gate electrode;
a source electrode and a drain electrode electrically connected to the active layer through a contact hole formed in the interlayer insulating layer and spaced apart from each other on the interlayer insulating layer; and
An oxide barrier layer electrically connected to one of the source electrode and the drain electrode and disposed on the interlayer insulating layer to overlap the gate electrode,
A thin film transistor in which opposite potentials are applied to the gate electrode and the oxide barrier layer. According to claim 1,
A thin film transistor, wherein the oxide barrier layer includes the same material as the active layer. According to clause 2,
The active layer and the oxide barrier layer include indium-gallium-zinc-oxide (IGZO), zinc oxide (ZnO), indium-zinc-oxide (IZO), indium-gallium-tin-oxide (IGTO), and indium-gallium-tin-oxide (IGO). A thin film transistor made of gallium-oxide) or a combination thereof. delete According to claim 1,
A thin film transistor in which a negative potential is applied to the gate electrode and a positive potential is applied to the oxide barrier layer. According to claim 1,
A thin film transistor, wherein the oxide barrier layer is in direct contact with the source electrode or the drain electrode. According to claim 1,
A thin film transistor wherein the oxide barrier layer has a thickness of 200Å to 600Å. According to claim 1,
A thin film transistor, wherein the oxide barrier layer completely covers the top of the gate electrode. According to clause 8,
The interlayer insulating layer is disposed to cover the active layer, the gate insulating layer, and the gate electrode, and the interlayer insulating layer forms a step in the area where the gate electrode is disposed,
The thin film transistor, wherein the oxide barrier layer is arranged to cover the step of the interlayer insulating layer. According to clause 9,
The interlayer insulating layer includes a gap formed in a portion adjacent to the gate electrode,
The thin film transistor, wherein the oxide barrier layer is disposed to contact the surface of the interlayer insulating layer to cover the air gap. A first thin film transistor comprising a low-temperature polysilicon material;
a second thin film transistor comprising an oxide semiconductor material;
an organic light emitting device disposed on the first thin film transistor and the second thin film transistor and including an anode, an organic light emitting layer, and a cathode; and
It includes an encapsulation portion disposed on the organic light emitting device,
The second thin film transistor has an oxide barrier layer made of oxide between the gate electrode and active layer of the second thin film transistor and the sealing part to block hydrogen generated in the encapsulation from flowing into the second thin film transistor. Contains,
A display device wherein opposing potentials are applied to the gate electrode and the oxide barrier layer. According to claim 11,
The first thin film transistor includes a first active layer made of a low-temperature polysilicon material, a first gate insulating layer on the first active layer, and a first gate electrode disposed on the first gate insulating layer and overlapping the first active layer. , a first interlayer insulating layer on the gate electrode, and a first source electrode and a first drain electrode disposed on the first interlayer insulating layer and connected to the first active layer,
The second thin film transistor includes a second active layer made of an oxide semiconductor material, a second gate insulating layer on the second active layer, a second gate electrode disposed on the second gate insulating layer and overlapping the second active layer, A display device comprising a second interlayer insulating layer on the gate electrode, and a second source electrode and a second drain electrode disposed on the second interlayer insulating layer and connected to the second active layer. According to claim 12,
The display device wherein the oxide barrier layer is disposed on the second interlayer insulating layer to overlap the second gate electrode and is in direct contact with the second source electrode and the second drain electrode. According to claim 12,
The second active layer and the oxide barrier layer include indium-gallium-zinc-oxide (IGZO), zinc oxide (ZnO), indium-zinc-oxide (IZO), indium-gallium-tin-oxide (IGTO), and IGO ( indium-gallium-oxide) or a combination thereof. According to claim 12,
The display device wherein the oxide barrier layer is disposed to cover a top and a side of the second gate electrode. According to claim 12,
The first thin film transistor is a driving thin film transistor,
The display device wherein the second thin film transistor is a switching thin film transistor.

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