KR20070071490A - Organic electroluminescence display device method for the same - Google Patents

Abstract

An organic electroluminescence display device and a fabrication method thereof are provided to reduce fabrication cost and process time, by reducing the number of usage of a photo mask by forming a capacitor bottom electrode at the same time when forming a semiconductor layer. A semiconductor layer(114) is formed on a substrate and includes a source region(114a) and a drain region(114c). A capacitor bottom electrode(114d) is comprised in the same layer as the semiconductor layer. A gate insulator(116) is formed on the front including the semiconductor layer and the capacitor bottom electrode. A gate electrode and a capacitor top electrode(122) are formed on the gate insulator on the top of the capacitor bottom electrode and the semiconductor layer. A source electrode(115a) and a drain electrode(115b) are insulated from the gate electrode and contact with the source/drain region. A first electrode is insulated from the source/drain electrode and contacts with the drain electrode. A hole transportation layer(132), an organic emission layer(133) and an electron transportation layer(134) are formed on the first electrode. A second electrode is formed on the top of the organic emission layer.

Description

Organic electroluminescent device and its manufacturing method {Organic Electroluminescence Display Device Method For The Same}

1 is a circuit diagram of one pixel of an active matrix organic electroluminescent device according to the prior art.

2 is a cross-sectional view of an organic electroluminescent device according to the present invention.

3A to 3E are cross-sectional views of an organic electroluminescent device according to the present invention.

* Explanation of symbols on the main parts of the drawings

111 substrate 112 gate electrode

113: buffer layer 114: semiconductor layer

114a: source area 114b: channel area

114c: drain region 114d: capacitor lower electrode

115a: source electrode 115b: drain electrode

116: gate insulating film 118: first interlayer insulating film

119: second interlayer insulating film 120: third interlayer insulating film

122: capacitor upper electrode 131: anode electrode

132: hole transport layer 133: organic light emitting layer

134: electron transport layer 135: cathode electrode

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electroluminescent display device (hereinafter referred to as ELD), and in particular, to form a lower electrode of a capacitor when forming a semiconductor layer at the same time to reduce the number of times of use of the mask to reduce manufacturing costs and process time An organic electroluminescent device and a method of manufacturing the same.

In recent years, research on flat panel displays has been actively conducted. Among them, liquid crystal displays (LCDs), field emission displays (FEDs), electroluminescence devices (ELDs), and plasma display panels (PDPs) have been in the spotlight.

Among them, liquid crystal display devices are widely used in personal information terminals, laptops, and TVs, including personal communication service (PCS). However, due to the problem that the viewing angle is narrow and the response speed is slow, self-luminous organic electroluminescent devices are attracting attention. have.

The organic electroluminescent device applies an electric field to the cathode and the anode formed at both ends of the organic EL layer to inject and transfer electrons and holes in the organic EL layer to bond with each other, thereby electroluminescence (EL) emitted by the binding energy at this time. It is using the phenomenon. That is, after electrons and holes are paired, light is emitted while falling from an excite state to a ground state.

Such an organic electroluminescent device has an advantage of being able to adapt to various tastes of modern people because it can realize a low voltage driving due to thinning and fast response speed and excellent brightness. In addition, there is an advantage that the device can be formed on a flexible transparent substrate, such as plastic.

In addition, the device is suitable for the next-generation flat panel display because it can be driven at a lower voltage than the PDP, has a relatively low power consumption, and can easily realize three colors of green, red, and blue.

Hereinafter, an organic electroluminescent device of the prior art will be described in more detail with reference to the accompanying drawings.

1 is a circuit diagram of one pixel of an active matrix organic electroluminescent device according to the prior art.

Recently, an active matrix form in which a plurality of pixels are arranged in a matrix form and thin film transistors are connected to each pixel is widely used in a flat panel display device, which is applied to an organic electroluminescence device and is used as an active matrix organic LED. matrix organic).

One pixel of the active matrix organic LED, as shown in FIG. 1, includes a switching thin film transistor 4, a driving thin film transistor 5, a storage capacitor 6, and light emission. It consists of a diode 7. Here, the switching thin film transistor 4 and the driving thin film transistor 5 are made of a p-type polycrystalline silicon thin film transistor.

In this case, the gate electrode of the switching thin film transistor 4 is connected to the gate line 1, and the source electrode is connected to the data line 2. The drain electrode of the switching thin film transistor 4 is connected to the gate electrode of the driving thin film transistor 5, and the drain electrode of the driving thin film transistor 5 is connected to the anode electrode of the light emitting diode 7.

The source electrode of the driving thin film transistor 5 is connected to a power line 3, and the cathode of the light emitting diode 7 is grounded. Next, the storage capacitor 6 is connected to the gate electrode and the source electrode of the driving thin film transistor 5.

Therefore, when a signal is applied through the gate wiring 1, the switching thin film transistor 4 is turned on, and the signal of the data wiring 2 is transmitted to the gate electrode of the driving thin film transistor 5, thereby driving the thin film transistor ( Since 5) is turned on, light is output through the light emitting diode 7.

In this case, when the switching thin film transistor 4 is turned off, the storage capacitor 6 maintains the gate voltage of the driving thin film transistor 5 constant.

For reference, the light emitting diode 7 is composed of a laminated film of an anode electrode, a hole injection layer, a hole transport layer, an organic light emitting layer, an electron transport layer, an electron injection layer, a cathode electrode.

Such active matrix organic electroluminescent devices form various patterns such as driving devices, wirings, storage capacitors, and light emitting diodes on a substrate to perform an operation, and among the techniques used to form the patterns, photolithography is a common technique. to be.

In the photolithography technique, a photoresist, which is a material that is photosensitive with ultraviolet rays, is coated on a substrate on which a pattern is to be formed, and a pattern formed on an exposure mask is exposed on a photoresist to be developed, and the patterned photoresist is used as a mask to form a desired material. It consists of a series of complicated processes of stripping the photoresist after etching the layer. Recently, research on "low mask technology" has been actively conducted to reduce the number of photoetch techniques to increase productivity and to secure process margins. It is becoming.

The present invention has been made to solve the above problems, the organic electroluminescent device to reduce the manufacturing cost and process time by reducing the number of times of use of the exposure mask by forming a capacitor lower electrode at the same time when forming the semiconductor layer and its The purpose is to provide a manufacturing method.

An organic electroluminescent device according to the present invention for achieving the above object is a semiconductor layer formed on a substrate including a source / drain region, a capacitor lower electrode provided in the same layer integrally with the semiconductor layer, A gate insulating film formed on the front surface including the semiconductor layer and the capacitor lower electrode, a gate electrode and a capacitor upper electrode formed on the gate insulating film on the semiconductor layer and the capacitor lower electrode, respectively, and the source / drain region insulated from the gate electrode A source / drain electrode contacted to the first electrode, a first electrode insulated from the source / drain electrode and contacted with the drain electrode, a hole transport layer, an organic light emitting layer and an electron transport layer formed on the first electrode, and an upper portion of the organic light emitting layer It is characterized by including a second electrode to be formed.

On the other hand, a method of manufacturing an organic electroluminescent device for achieving another object of the present invention comprises the steps of forming a semiconductor layer and a capacitor lower electrode integral with each other on a substrate, storage doping the capacitor lower electrode, and Forming a gate insulating film on the entire surface including the semiconductor layer, forming a gate wiring, a gate electrode, and an upper capacitor electrode on the gate insulating film, and implanting impurities into the semiconductor layer using the gate electrode as a mask / Forming a drain region, forming a data wiring crossing the gate wiring, a source / drain electrode insulated from the gate electrode and contacting the source / drain region, and insulated from the source / drain electrode Forming a first electrode in contact with said drain electrode, wherein said first electrode is formed on said first electrode; Forming an electron transport layer, an organic light emitting layer, and a hole transport layer, and forming a second electrode on the organic light emitting layer.

Hereinafter, an organic electroluminescent device and a method of manufacturing the same according to the present invention will be described with reference to the accompanying drawings.

2 is a cross-sectional view of an organic electroluminescent device according to the present invention, and FIGS. 3a to 3e are process cross-sectional views of the organic electroluminescent device according to the present invention.

The organic electroluminescent device according to the present invention includes an active region including a thin film transistor, a wiring, a light emitting diode, and a storage capacitor, and a pad portion region connected to an external driving circuit to apply various signals to the active region.

Specifically, although not shown, sub-pixels are defined by gate lines arranged in a line and data lines and power supply lines vertically crossing the gate lines and spaced apart from each other at regular intervals.

In this case, the switching thin film transistor Ts is disposed at the intersection point of the gate line and the data line, and the driving thin film transistor Tp is disposed at the intersection point of the gate line and the power supply line.

As shown in FIG. 2, a thin film transistor such as a switching thin film transistor Ts or a driving thin film transistor Tp is a top-gate type, and has source / drain regions 114a and 114c and a channel region 114b doped with impurities. ), A gate insulating film 116 formed on the entire surface including the semiconductor layer, a gate electrode 112 overlapping an upper portion of the channel region 114b of the semiconductor layer on the gate insulating film, and A first interlayer insulating film 118 formed on the entire surface including the gate electrode 112, and source / drain electrodes 115a and 115b respectively contacting the source / drain regions on the first interlayer insulating film, and formed in the pixel. Control the turn-on or turn-off of the voltage.

In this case, the drain electrode 115b of the thin film transistor is electrically connected to the anode electrode 131.

The storage capacitor includes a capacitor lower electrode 114d, which is an extension of the impurity doped semiconductor layer 114, a capacitor upper electrode 122 disposed on the same layer as the gate electrode 112, and interposed therebetween. The gate insulating layer 116 is formed to reduce the level-shift voltage and maintain the charged charge during the turn-off period of the thin film transistor (during the non-selection period). In this case, the capacitor upper electrode extends to the outside of the active region to receive a voltage from outside the active region, and the capacitor lower electrode is formed by storage doping to the extension of the semiconductor layer.

Meanwhile, the light emitting diode includes an anode electrode 131, a hole injection layer (not shown), a hole transport layer 132, an organic light emitting layer 133, an electron transport layer 134, an electron injection layer (not shown), and a cathode. It consists of a laminated film of electrodes 135.

When an electric field is applied to the anode electrode 131 and the cathode electrode 135 of the device, electrons are injected into the organic light emitting layer 133 from the cathode, and holes are injected into the organic light emitting layer 133 from the anode 131. In this case, the electrons and holes injected into the organic light emitting layer 133 move to the organic light emitting layer under an electric field, and combine with each other to form an exciton. , Electroluminescence).

For reference, the organic light emitting layer 133 is a light unique to each sub-pixel, for example, and expresses colors of red (R), green (G), and blue (B). It is formed by patterning a separate organic material emitting green, green and blue.

In the pad region, a gate pad for applying a gate driving signal to each of the gate lines, a plurality of data pads for applying a data signal to the data lines, and a plurality of pads for supplying power to each power supply line A power supply pad is provided, and the pad electrode 125 including the gate pad, the data pad, and the power supply pad is covered by the antioxidant layer 130 through an open area from which the second interlayer insulating layer 119 is removed.

In this case, the antioxidant layer 130 is provided on the same layer as the anode electrode 131 in the active region.

Looking at the manufacturing method of the organic EL device in detail as follows.

First, as shown in FIG. 3A, amorphous silicon is deposited on the substrate 111, and then the silicon is crystallized into polycrystalline silicon by rapidly melting and solidifying by applying heat thereon with a laser or the like.

In this case, the buffer layer 113 may be further formed under the amorphous silicon, and the buffer layer is made of an insulating material such as silicon oxide (SiOx), and serves to prevent foreign substances from the substrate from penetrating into the polycrystalline silicon in a subsequent process. Do it.

Next, by using a photolithography technique using a first exposure mask, the polycrystalline silicon is patterned to form a semiconductor layer 114 and a capacitor lower electrode 114d integral with the semiconductor layer.

Thereafter, a second exposure mask is disposed to open the capacitor lower electrode, and then storage doping is performed. As a result, the storage lower capacitor 114d is formed on the extension of the semiconductor layer.

Subsequently, an inorganic insulating material such as an oxide or nitride is deposited on the entire surface of the substrate 111 by the plasma enhanced chemical vapor deposition (PECVD) method to form the gate insulating layer 116.

The metal layer on the gate insulating layer 116 may include, for example, copper (Cu), aluminum (Al), aluminum alloy (AlNd), molybdenum (Mo), chromium (Cr), titanium (Ti), tantalum (Ta), Molybdenum-tungsten (MoW) and the like are deposited and the gate electrode 112 and the capacitor upper electrode 122 are formed by photolithography using a third exposure mask.

In this case, the gate electrode 112 extends to branch from the gate line, and is formed in a predetermined region so as to overlap the channel region of the thin film transistor to be formed later.

The capacitor upper electrode 122 is formed parallel to the gate line, but overlaps with the capacitor lower electrode 114d to form a storage capacitor.

Thereafter, impurities are ion-implanted using the gate electrode 112 and the capacitor upper electrode 122 as an exposure mask to form source / drain regions 114a and 114c in the semiconductor layer 114. At this time, the semiconductor layer between the source region and the drain region where the impurity ions are not implanted becomes the channel region 114b.

During implantation of the impurity ions, a p-type source / drain region is formed by doping a high concentration of p-type impurity ions using boron (B) or the like.

Next, as illustrated in FIG. 3B, an inorganic insulating material such as silicon oxide or silicon nitride is deposited on the entire surface of the substrate including the gate electrode 112 by PECVD, or an organic insulating material such as BCB or acrylic resin is coated. After the first interlayer insulating layer 118 is formed, a first contact hole (not shown) may be formed to expose predetermined portions of the source / drain regions 114a and 114c by applying a photolithography technique using a fourth exposure mask. Form.

Subsequently, on the first interlayer insulating layer 118, as a metal layer, for example, copper (Cu), aluminum (Al), aluminum alloy (AlNd), molybdenum (Mo), chromium (Cr), titanium (Ti), and tantalum ( Ta /, molybdenum-tungsten (MoW), etc., and a source / drain electrode 115a contacting the data line (not shown) and the source / drain regions 114a and 114c by a photoetching technique using a fifth exposure mask. 115b). At this time, the pad electrode 125 is simultaneously formed in the pad region.

3C, an inorganic insulating material such as silicon nitride or silicon oxide is deposited on the entire surface including the source / drain electrodes 115a and 115b, or an organic insulating material such as benzocyclobutene (BCB) or an acrylic material. Is applied to form a second interlayer insulating film 119.

Subsequently, the second interlayer insulating layer 119 is etched using a photolithography technique using a sixth exposure mask to open the second contact hole 151 and the pad electrode 125 where the drain electrode 115b is exposed. 152).

As shown in FIG. 3D, an anode electrode contacting the drain electrode 115b is deposited by depositing a metal layer of Al, AlNd, Ag, etc. having reflective properties on the entire surface of the substrate, and using a photoetching technique using a seventh exposure mask. 131 and an anti-oxidation film 130 covering the pad electrode.

At this time, it is possible to further deposit ITO (Indium Tin Oxide) on the metal layer, the reason for depositing the ITO energy band gap (Energy band gap) to facilitate the inflow of holes from the anode electrode to the hole transport layer to be formed later To reduce the difference.

Thereafter, a thick insulating film is deposited or coated on the anode electrode 131 and patterned by photolithography using an eighth exposure mask to form a bank 200 in which most of the anode electrode 131 is exposed.

After forming the array substrate of the active matrix organic LED as described above, the active matrix organic LED is formed by forming the hole transport layer 132, the organic emission layer 133, the electron transport layer 134, and the cathode electrode 135 on the bank 200. To complete.

In this case, the hole transport layer 132, the organic light emitting layer 133, the electron transport layer 134, and the cathode electrode 135 may use a shadow mask without applying a photoetching technique using an exposure mask. Limited to form.

 On the other hand, the present invention described above is not limited to the above-described embodiment and the accompanying drawings, it is possible that various substitutions, modifications and changes within the scope without departing from the technical spirit of the present invention. It will be apparent to those of ordinary skill in Esau.

That is, in the above embodiment, the source / drain region is limited by doping the p-type impurity, but the n-type source / drain region may be formed by doping a high concentration of n-type impurity ions using phosphorus (P). have. In this case, the light emitting diode may be formed of a laminated film of a cathode electrode, an electron injection layer, an electron transport layer, an organic light emitting layer, a hole transport layer, a hole injection layer, and an anode electrode.

The organic electroluminescent device of the present invention as described above and a method of manufacturing the same have the following effects.

First, when the semiconductor layer is formed, the capacitor lower electrode is formed at the same time, thereby reducing the number of times of use of the exposure mask, thereby reducing manufacturing costs and processing time.

Second, the storage capacitor according to the present invention includes an extension portion (capacitor lower electrode), a gate insulating film, and a capacitor upper electrode of the semiconductor layer. Since the dielectric constant of the gate insulating film is larger than that of other interlayer insulating films, the storage capacitance is increased. Can be.

Claims (9)

A semiconductor layer formed on the substrate and including a source / drain region; A capacitor lower electrode provided on the same layer as an integrated body with the semiconductor layer; A gate insulating film formed on the entire surface including the semiconductor layer and the capacitor lower electrode; A gate electrode and a capacitor upper electrode formed on the gate insulating layer on the semiconductor layer and the capacitor lower electrode, respectively; A source / drain electrode insulated from the gate electrode and in contact with the source / drain region; A first electrode insulated from the source / drain electrode and in contact with the drain electrode; A hole transport layer, an organic light emitting layer, and an electron transport layer formed on the first electrode; An organic electroluminescent device, characterized in that it comprises a second electrode formed on the organic light emitting layer. The method of claim 1, And the source / drain region is a p-type or n-type source / drain region. The method of claim 1, And the capacitor lower electrode is formed by storage doping at an extension of the semiconductor layer. The method of claim 1, And the semiconductor layer, the gate insulating film, the gate electrode, and the source / drain electrode are switching thin film transistors or driving thin film transistors. Forming an integrated semiconductor layer and a capacitor lower electrode on the substrate; Storage doping the capacitor lower electrode; Forming a gate insulating film on the entire surface including the semiconductor layer; Forming a gate wiring, a gate electrode, and a capacitor upper electrode on the gate insulating film; Implanting impurities into the semiconductor layer using the gate electrode as a mask to form a source / drain region; Forming a data line crossing the gate line and a source / drain electrode insulated from the gate electrode and in contact with the source / drain region; Forming a first electrode in contact with the drain electrode insulated from the source / drain electrode; Forming an electron transport layer, an organic light emitting layer, and a hole transport layer on the first electrode; A method of manufacturing an organic electroluminescent device, comprising the step of forming a second electrode on the organic light emitting layer. The method of claim 5, The semiconductor layer is formed of polycrystalline silicon. The method of claim 5, The capacitor lower electrode is a method of manufacturing an organic electroluminescent device, characterized in that formed by extending the semiconductor layer. The method of claim 5, Implanting impurities into the semiconductor layer to form a source / drain region; A method of manufacturing an organic electroluminescent device, characterized by injecting n-type impurities or injecting p-type impurities. The method of claim 5, And the gate insulating film is formed of an oxide film or a nitride film.

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