CN1292394C - Electroluminescent display device and manufacturing method thereof - Google Patents

Abstract

The invention discloses a top-emitting electroluminescent display device, which comprises: a thin film transistor, a non-transparent electrode, a non-transparent layer, an electroluminescent medium layer, and a transparent electrode. The thin film transistor is arranged above a substrate and covered by an intermediate insulating layer. The non-transparent electrode and the non-transparent layer are sequentially arranged above the intermediate insulating layer, wherein the non-transparent electrode is electrically connected with the thin film transistor, and the non-transparent layer is provided with an opening to expose a part of the non-transparent electrode below. The electroluminescent medium layer is disposed at the bottom of the opening. The transparent electrode is arranged above the non-transparent layer and conforms to the surface of the opening and the surface of the electroluminescent medium layer to cover the opening and the electroluminescent medium layer. The invention also relates to a manufacturing method of the electroluminescent display device.

Description

Electroluminescent display device and manufacturing method thereof

technical field

The present invention relates to a flat display device, in particular to a top emission type electro-luminescence display device (electro-luminescence device) and a manufacturing method thereof.

Background technique

An electroluminescent device, such as an organic light emitting diode (OLED), is a self-luminous device using organic materials. Typically, an OLED includes: an anode, a cathode, and an electro-luminescence medium layer (EML) disposed between the anode and the cathode. When a potential difference is applied between the cathode and the anode, electrons and holes are respectively injected into the electroluminescence medium layer from the cathode and the anode to recombine and release energy in the form of light.

FIG. 1 is a schematic cross-sectional view of a conventional bottom emitting electroluminescent display device. 1, a buffer layer 102 is formed on a substrate 100, and a thin film transistor 111 is disposed on the buffer layer 102, which includes a channel layer 104, gate dielectric layer 106, gate electrode 107, and source /drain electrode 109 . A channel layer 104 , such as a polysilicon layer, is formed on the buffer layer 102 and has source/drain doped regions 105 . The top of the channel layer 104 is covered by an insulating layer 106, such as a silicon nitride layer, serving as the gate dielectric layer. The gate electrode 107 is disposed above the gate dielectric layer 106 above the channel layer 104 and is covered by an interlayer dielectric (ILD) layer 108 . Source/drain electrodes 109 are disposed on both sides of the gate electrode 107 , which are electrically connected to the source/drain doped region 105 via an interlayer dielectric layer and a contact hole in the underlying insulating layer 106 . A first passivation layer 110 covers the thin film transistor 111 and the interlayer dielectric layer 108 , and has a via hole exposing one of the source/drain electrodes 109 . A transparent electrode 112, such as indium tin oxide (ITO), is formed on a part of the first protective layer 110 and electrically connected to the exposed source/drain electrodes 109 through via holes. The second protective layer 114 is disposed on the first protective layer 110 above the TFT 111 . An electroluminescent medium layer 116 covers the second protective layer 114 and the transparent electrode 112 , and a non-transparent electrode 118 , such as a metal material, is formed on the electroluminescent medium layer 116 .

In the electroluminescence display device of FIG. 1 , the transparent electrode 112 serves as an anode, and the non-transparent electrode 118 serves as a cathode. Therefore, light is emitted downward from the electroluminescent medium layer 116 through the transparent electrode 112 . This is called a bottom emitting electroluminescent display device. However, the light emitting area of a bottom emitting electroluminescent display device is limited by thin film transistors. When the number of thin film transistors in a display device increases, the aperture ratio of the electroluminescence display device will shrink. In order to maintain the brightness of the panel, the power consumption will increase, which shortens the life of the electroluminescent display device.

Contents of the invention

In view of this, the object of the present invention is to provide an electroluminescence display device and a manufacturing method thereof, which emit light upward so that the light emitting area (or aperture ratio) is not limited by the thin film transistor.

Another object of the present invention is to provide an electroluminescent display device and its manufacturing method, which avoids side leakage of light by an opaque layer surrounding the light emitting region, thereby preventing color wash of the electroluminescent display device. out).

According to the above-mentioned purpose, the present invention provides an electroluminescence display device, which includes: a substrate having a first region and a second region, a thin film transistor, an intermediate insulating layer, a non-transparent electrode, a non-transparent layer, an electroluminescence medium layer, and a transparent electrode. The thin film transistor is disposed above the first region of the substrate, and the intermediate insulating layer is disposed above the second region of the substrate and covers the thin film transistor. The non-transparent electrode is arranged on the middle insulating layer and electrically connected with the thin film transistor, and the non-transparent layer is arranged on the top of the non-transparent electrode, and has an opening to expose a part of the non-transparent electrode. The electroluminescent medium layer is disposed at the bottom of the opening. The transparent electrode is disposed above the non-transparent layer and covers the openings and the surface of the electroluminescent medium layer along with them.

Also according to the above purpose, the present invention provides a method for manufacturing an electroluminescent display device. Firstly, a substrate is provided, which has a first region and a second region, a thin film transistor is formed on the first region of the substrate, and then an intermediate insulating layer is formed on the second region of the substrate to cover the thin film transistor. Afterwards, a non-transparent electrode is formed on the intermediate insulating layer and electrically connected with the thin film transistor, and then a non-transparent layer is formed on the non-transparent electrode, which has an opening to expose a part of the non-transparent electrode. Subsequently, an electroluminescent medium layer is formed on the exposed portion of the non-transparent electrode, and a transparent electrode is formed on the non-transparent layer, and covers the opening and the surface of the electroluminescent medium layer in conformity with them.

In order to make the above objects, features and advantages of the present invention more comprehensible, preferred embodiments are specifically cited below and described in detail with accompanying drawings.

Description of drawings

FIG. 1 is a schematic cross-sectional view of a conventional bottom emitting electroluminescent display device.

2A to 2F are cross-sectional schematic diagrams illustrating a method of manufacturing a top emission electroluminescence display device according to an embodiment of the present invention.

simple notation

existing

100～substrate; 102～buffer layer; 104～channel layer; 105～source/drain doped region; 106～gate dielectric layer; 107～gate electrode; 108～interlayer dielectric layer; 109～source Pole/drain electrode; 110~first protective layer; 111~thin film transistor; 112~transparent electrode; 114~second protective layer; 116~electroluminescence medium layer; 118~non-transparent electrode.

this invention

10～first area; 20～second area; 200～substrate; 202～buffer layer; 204～channel layer; 206～gate dielectric layer; 207～gate electrode; 209～ion implantation; 210～interlayer dielectric Electrical layer; 211～source/drain doped region; 212～intermediate insulating layer; 213～source/drain electrode; 214～non-transparent electrode; 215～thin film transistor; 216～transparent conductive layer; 217, 219, 221～opening; 218insulating layer; 220～non-transparent layer; 222～electroluminescent medium layer; 224～transparent electrode; 226～electroluminescent diode.

Detailed ways

FIG. 2F is a schematic cross-sectional view of a top emitting electroluminescent display device according to an embodiment of the present invention. The electroluminescence display device includes: a substrate 200 having a first region 10 and a second region 20, a thin film transistor 215, an intermediate insulating layer 212, a non-transparent electrode 214, a non-transparent layer 220, an electro-excitation The optical medium layer 222 and a transparent electrode 224 . Here, the first region of the substrate 200 may be a transistor region, and the second region 20 may be a light emitting region. Furthermore, a buffer layer 202 is covered thereon. The thin film transistor 215 is disposed on the buffer layer 202 above the first region 10 of the substrate 200, which consists of a channel layer 204 having a source/drain doped region 211, a gate dielectric layer 206, a gate electrode 207, and a source electrode/drain electrode 213. An interlayer dielectric (ILD) layer 210 is disposed on the gate dielectric layer 206 and covers the gate electrode 207 .

The intermediate insulating layer 212 is disposed on the interlayer dielectric (ILD) layer 210 above the second region 20 of the substrate 200 and covers the thin film transistor 215 above the first region 10 . Here, the intermediate insulating layer 212 has an opening exposing one of the source/drain electrodes 213 .

The non-transparent electrode 214 is disposed on the intermediate insulating layer 212 and is electrically connected to the thin film transistor 215 through the exposed source/drain electrode 213 . The height of the non-transparent electrode 214 above the second region 20 of the substrate 200 is higher than that of the thin film transistor 215 above the first region 10 . A transparent conductive layer 216 can be selectively disposed on the non-transparent electrode 214 as a part of the electrode 214, so that the work function of the electrode 214 can be matched with the subsequently formed electroluminescence medium layer.

An insulating layer (covering layer) 218 and a non-transparent layer 220 are sequentially disposed above the non-transparent electrode 214, wherein the insulating layer 218 has an opening 219 located above the second region 20 of the substrate 200 to expose a portion formed with a transparent conductive layer 216. The non-transparent layer 220 has an opening 221 located above the opening 219 . Here, the opening 221 is larger than the opening 219 to further increase the aperture ratio. The electroluminescence medium layer 222 is disposed at the bottom of the openings 221 and 219 . The transparent electrode 224 is disposed above the non-transparent layer 220 and conforms to the surface of the opening 221 and the electroluminescence medium layer 222 to cover them.

When a potential difference is applied between the electrodes 214 and 224 , electrons and holes will be injected into the electroluminescence medium layer 222 from different electrodes 214 and 224 and recombine to emit light. In this embodiment, the light is reflected upward by the non-transparent electrode 214 . In this way, even if the number of thin film transistors increases, their light emitting area (or aperture ratio) will not decrease. Therefore, the brightness of the electroluminescence display device is maintained or increased. In other words, the lifetime of the electroluminescence display device is extended without increasing the power consumption. Moreover, according to the electroluminescent display device of the present invention, the non-transparent layer 220 disposed above the non-transparent electrode 214 can block light from escaping from both sides of the electroluminescent medium layer 222, thereby preventing color shift in the electroluminescent display device. Phenomenon. That is, the display quality of the top emission electroluminescence display device can be improved.

The manufacturing method of the top emission electroluminescence display device according to the embodiment of the present invention will be described below with reference to FIGS. 2A to 2F . First, please refer to FIG. 2A , a substrate 200 is provided, such as a glass or quartz substrate, which has a plurality of transistor regions and light emitting regions for forming thin film transistors and electroluminescent diodes thereon. Here, to simplify the drawing, only a first region 10 and a second region 20 are shown. For example, the first region 10 represents a transistor region, and the second region 20 represents a light emitting region. Next, a buffer layer 202 is formed on the substrate 200 . The buffer layer 202 can be a single layer structure or a stacked layer structure. For example, the buffer layer 202 may be composed of a silicon nitride layer and an overlying silicon oxide layer. Next, a semiconductor layer (not shown) is formed on the buffer layer 202, and then the semiconductor layer is defined by existing photolithography and etching processes, so as to form a patterned semiconductor layer 204 above the first region 10 of the substrate 200, so as to as the channel layer of thin film transistors.

Next, please refer to FIG. 2B , an insulating layer 206 , such as a silicon nitride layer, is formed on the buffer layer 202 and covers the channel layer 204 to serve as a gate dielectric layer of the thin film transistor. Afterwards, a metal layer (not shown) is formed on the insulating layer 206, and the metal layer is defined by existing photolithography and etching processes to form a patterned metal layer 207 above the first region 10 of the substrate 200 as a The gate electrode of the thin film transistor. Next, using the gate electrode 207 as a mask, an ion implantation process 209 is performed on the lower channel layer 204 to form a source/drain doped region 211 therein.

Next, an interlayer dielectric (ILD) layer 210 is deposited over the substrate shown in FIG. 2B. Subsequently, a contact window penetrating through the interlayer dielectric layer 210 and the insulating layer 206 is formed on both sides of the gate electrode 207 by an etching process to expose the source/drain doped region 211 , as shown in FIG. 2C .

Next, referring to FIG. 2D , a metal layer (not shown) is formed on the interlayer dielectric layer 210 and filled into the contact hole to be electrically connected to the source/drain doped region 211 . Afterwards, the metal layer is defined by conventional photolithography and etching processes to form the source/drain electrodes 213 , and the fabrication of the thin film transistor 215 is completed on the first region 10 of the substrate 200 . Next, an interlayer insulating layer (interlayer insulator) 212 is deposited on the interlayer dielectric layer 210 above the first and second regions 10 and 20 of the substrate 200 and covers the thin film transistor 215 as a flat layer. Next, an opening 217 is formed in the intermediate insulating layer 212 to expose one of the source/drain electrodes 213 .

Next, referring to FIG. 2E , a non-transparent conductive layer 214 is formed on the intermediate insulating layer 212 and fills the opening 217 to be electrically connected to the exposed source/drain electrodes 213 . The non-transparent conductive layer 214 serves as an electrode and a light reflection layer of the OLED. The non-transparent electrode 214 can be a single layer or multiple metal layers. For example, it may be composed of any one of aluminum, silver, gold, titanium, nickel, chromium, copper, iron, manganese, platinum, zinc, and alloys thereof. In this embodiment, the non-transparent conductive layer 214 located above the second region 20 of the substrate 200 is higher than the thin film transistor 215 , so that the subsequently formed electroluminescence medium layer can be higher than the thin film transistor 215 to increase its aperture ratio. Next, a transparent conductive layer 216 such as indium tin oxide (ITO) or indium zinc oxide (IZO) can be optionally deposited on the non-transparent electrode 214 . The transparent conductive layer 216 is a part of the electrode 214 of the electroluminescence diode, so that the work function of the electrode 214 can be matched with the subsequently formed electroluminescent medium layer. It should be noted that if there is no transparent conductive layer 216 between the subsequently formed electroluminescent medium layer and the electrode 214, the electroluminescent medium layer must be additionally doped so that the work function of the electrode 214 can be compared with that of the electroluminescent medium. layer match.

Next, an insulating layer (covering layer) 218 is formed on the non-transparent electrode 214 having the transparent conductive layer 216 formed thereon. Afterwards, an opening 219 is formed in the insulating layer 218 above the second region 20 of the substrate 200 .

Finally, referring to FIG. 2F , the key steps of the present invention are performed, forming an opaque layer 220 on the insulating layer 218 . As mentioned above, the opaque layer 220 is used to prevent light from escaping from both sides of the subsequently formed electroluminescent medium layer, thereby avoiding the color shift phenomenon caused by light leakage. In this embodiment, the material of the non-transparent layer 220 may be any one of a metal layer, a metal oxide layer, an organic material layer (such as a photoresist), and a polymer. Preferably, the material of the opaque layer 220 is a metal layer. For example, it may be composed of any one of aluminum, silver, gold, titanium, nickel, chromium, copper, iron, manganese, platinum, zinc, and alloys thereof. Furthermore, it can be a single-layer or multi-layer structure, like the non-transparent electrode 214 . When the material of the non-transparent layer 220 is a metal layer, side leakage light will be trapped in the waveguide formed by the non-transparent electrode 214 and the non-transparent layer 220 , thereby reducing the chance of light leakage. Next, another opening 221 is formed in the non-transparent layer 220 above the opening 219, which is preferably larger than the opening 219, so as not to block the light emitted from the electroluminescence medium layer (EML) formed later. Afterwards, an electroluminescent medium layer 222 is formed at the bottom of the openings 219 and 221, which can be a single-layer or multi-layer structure. In this embodiment, for example, the electroluminescence medium layer 222 is a multilayer structure and includes: a hole transport layer (hole transport layer, HTL), an electron transport layer (electron transport layer, ETL), and a set An active or emissive layer between the hole transport layer and the electron transport layer. Here, in order to simplify the diagram, it is represented by a single-layer structure. Next, form a transparent electrode 224 on the non-transparent layer 220, such as indium tin oxide (ITO) or indium zinc oxide (IZO), and conform to the surface of the opening 221 and the electroluminescent medium layer 222 to cover them, so that The fabrication of the electroluminescent diode 226 is completed above the second region 20 of the substrate 200 . Since light is emitted upwards from the electroluminescent medium layer 222, it is called a top-emitting electroluminescent display device.

In addition, in another embodiment of the present invention, the non-transparent layer 220 may be directly formed on the non-transparent electrode 214 . That is, there is no insulating layer 218 between the non-transparent layer 220 and the non-transparent electrode 214 . However, it should be noted that the non-transparent layer 220 needs to be an insulating material, such as any one of a metal oxide layer, an organic material layer (such as a photoresist), and a polymer.

Although the present invention is disclosed above with preferred embodiments, it is not intended to limit the present invention. Those skilled in the art can make some changes and modifications without departing from the spirit and scope of the present invention, so the protection scope of the present invention It shall prevail as defined in the appended claims.

Claims (20)

1. An electroluminescent display device, comprising: A substrate having a first area and a second area; a thin film transistor disposed above the first region of the substrate; an intermediate insulating layer disposed above the second region of the substrate and covering the thin film transistor; a non-transparent electrode disposed above the intermediate insulating layer and electrically connected to the thin film transistor; a non-transparent layer disposed above the non-transparent electrode, which has a first opening exposing a part of the non-transparent electrode; an electroluminescent medium layer disposed at the bottom of the first opening; and A transparent electrode is arranged on the non-transparent layer and conforms to the first opening and the surface of the electroluminescent medium layer to cover them. 2. The electroluminescence display device as claimed in claim 1, wherein the non-transparent electrode located above the second region is higher than the thin film transistor. 3. The electroluminescence display device as claimed in claim 1, further comprising an indium tin oxide layer disposed between the electroluminescence medium layer and the non-transparent electrode. 4. The electroluminescent display device as claimed in claim 1, wherein the non-transparent electrode comprises a metal layer. 5. The electroluminescence display device as claimed in claim 1, wherein the opaque layer comprises any one of an organic material layer, a metal oxide layer, and a polymer layer. 6. The electroluminescence display device as claimed in claim 1, further comprising an insulating layer disposed between the non-transparent electrode and the non-transparent layer, which has a second opening located below the first opening to expose the non-transparent layer. transparent electrodes. 7. The electroluminescence display device as claimed in claim 6, wherein the opaque layer comprises any one of a metal layer, a metal oxide layer, an organic material layer, and a polymer layer. 8. The electroluminescent display device as claimed in claim 6, wherein the first opening is larger than the second opening. 9. The electroluminescence display device as claimed in claim 1, wherein the first opening is located on the second region of the substrate. 10. The electroluminescence display device as claimed in claim 1, wherein the first opening spans the first region and the second region of the substrate. 11. A method for manufacturing an electroluminescence display device, comprising the following steps: providing a substrate having a first region and a second region; forming a thin film transistor over the first region of the substrate; forming an intermediate insulating layer over the second region of the substrate and covering the thin film transistor; forming a non-transparent electrode on the intermediate insulating layer and electrically connecting with the thin film transistor; forming a non-transparent layer above the non-transparent electrode, which has a first opening exposing a part of the non-transparent electrode; forming an electroluminescent medium layer over the exposed portion of the opaque electrode; and A transparent electrode is formed on the non-transparent layer, and covers the first opening and the surface of the electroluminescent medium layer along with them. 12. The method of manufacturing an electroluminescent display device as claimed in claim 11, wherein the non-transparent electrode located above the second region is higher than the thin film transistor. 13. The method for manufacturing an electroluminescence display device as claimed in claim 11, further comprising forming an indium tin oxide layer between the electroluminescence medium layer and the non-transparent electrode. 14. The method of manufacturing an electroluminescent display device as claimed in claim 11, wherein the non-transparent electrode comprises a metal layer. 15. The method for manufacturing an electroluminescent display device as claimed in claim 11, wherein the opaque layer comprises any one of an organic material layer, a metal oxide layer, and a polymer layer. 16. The method for manufacturing an electroluminescent display device as claimed in claim 11, further comprising forming an insulating layer between the non-transparent electrode and the non-transparent layer, which has a second opening located below the first opening and The non-transparent electrode is exposed. 17. The method for manufacturing an electroluminescent display device as claimed in claim 16, wherein the opaque layer comprises any one of a metal layer, a metal oxide layer, an organic material layer, and a polymer layer. 18. The method of manufacturing an electroluminescence display device as claimed in claim 16, wherein the first opening is larger than the second opening. 19. The method of manufacturing an electroluminescent display device as claimed in claim 11, wherein the first opening is located on the second region of the substrate. 20. The method of manufacturing an electroluminescence display device as claimed in claim 11, wherein the first opening spans the first region and the second region of the substrate.

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