KR20060113219A - Organic light emitting device - Google Patents

Abstract

An organic electroluminescent device is disclosed. The pixel driver and the organic light emitting diode constituting the organic light emitting display device are formed on separate substrates. That is, the pixel driver is formed on the single crystal silicon substrate, and the organic light emitting element is formed on the transparent substrate. The organic light emitting display device has a bottom emission structure, and the anode electrode and the cathode electrode are electrically connected to the semiconductor substrate on which the pixel driver is formed. The electrical connection between the pixel driver and the anode electrode and the cathode electrode of the organic light emitting diode is implemented by a bump provided in a pad formed on a single crystal silicon substrate.

Description

Organic Electroluminescence Display Device

1 is a cross-sectional view showing an active matrix organic light emitting display device according to the prior art.

2 is a circuit diagram illustrating a pixel circuit according to a preferred embodiment of the present invention.

3 is a plan view illustrating a layout of the organic light emitting display device according to the preferred embodiment of the present invention.

4A is a cross-sectional view when the pixel illustrated in FIG. 3 is cut along the line AA ′ according to the exemplary embodiment of the present invention.

4B is a cross-sectional view of the pixel of FIG. 3 taken along the line BB ′ according to an exemplary embodiment of the present invention.

5 is a cross-sectional view for describing the formation of the pixel driver of FIG. 2 on a single crystal silicon substrate according to a preferred embodiment of the present invention.

6 is a cross-sectional view showing the structure of an organic light emitting display device according to a preferred embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

101: pixel driver 310: light emitting area

312 lower electrode line 314 upper electrode line

316: lower electrode pad 318: upper electrode pad

500: single crystal silicon substrate 501A, 501B: bump

The present invention relates to an organic electroluminescent device, and more particularly, to an active matrix organic electroluminescent device.

The organic light emitting display device is a display device having self-luminous characteristics and is classified into a passive matrix type and an active matrix type according to a driving method.

The passive matrix type uses a manufacturing method of forming an anode electrode on a substrate, forming an organic film on the anode electrode, and forming a cathode electrode on the organic film. The anode electrode and the cathode electrode are formed to cross perpendicularly to each other, the organic film performs a light emitting operation in the region where the anode electrode and the cathode electrode intersect. However, the passive matrix type is required to apply a high voltage instantaneously in order to emit light of the organic film, and has the disadvantage of not having an active device and a passive device capable of maintaining the emission of the organic film for a certain period of time. Therefore, in order for the passive matrix type to display a predetermined image, a high voltage difference must be applied to the anode and the cathode electrode. The lifetime of the organic film is shortened by the application of a high voltage, causing a problem of high power consumption.

The active matrix type includes an active circuit inside the pixel to emit light of the organic film. That is, a scan signal for selecting a pixel on which the light emission operation is performed is applied, and a data signal is applied to the selected pixel in the scan signal. The driving current required for the light emission operation is generated by the applied data signal, which is maintained while the light emission operation is performed by the storage means provided in the pixel.

An active matrix type organic light emitting display device is divided into a voltage writing type and a current writing type according to a method of driving an organic light emitting display device.

In the voltage write type, the data signal for generating the drive current of the organic light emitting element is a voltage signal, and in the current write type, the data signal for generating the drive current of the organic light emitting element is a current signal.

1 is a cross-sectional view showing an active matrix organic light emitting display device according to the prior art.

Referring to FIG. 1, a buffer film 105 is formed on a substrate 100. The buffer film 105 may be a silicon oxide film, a silicon nitride film, a silicon oxynitride film, or a multilayer thereof.

The semiconductor layer 110 is formed on the buffer layer 105. The semiconductor layer 110 may be an amorphous silicon film or a polycrystalline silicon film obtained by crystallizing an amorphous silicon film. The gate insulating layer 115 is formed on the semiconductor layer 110. The gate insulating film 115 may be a silicon oxide film, a silicon nitride film, a silicon oxynitride film, or a multilayer thereof.

A gate electrode 121 overlapping the semiconductor layer 110 is formed on the gate insulating layer 115, and a first interlayer insulating layer 127 is formed on the gate electrode 121 and the semiconductor layer 110. . In addition, contact holes are formed in the first interlayer insulating layer 127 to expose both ends of the semiconductor layer 110. The contact hole is filled with a conductive material and formed as a source electrode 132 and a drain electrode 131.

Subsequently, a passivation film 140 and a planarization film 141 are formed to completely apply the source electrode 132, the drain electrode 131, and the first interlayer insulating film 127. The passivation film 140 is formed of a silicon nitride film that blocks moisture from the outside. In addition, the planarization film 141 is a polyimide film or a polyacryl film that can reduce the step.

Subsequently, the planarization layer 140 and the passivation layer 141 are patterned to form a plug 151. In addition, the plug 151 is formed of a conductive material. Subsequently, a transparent electrode 161 is formed on the plug. The transparent electrode 161 is formed of indium tin oxide (ITO) or indium zinc oxide (IZO).

The pixel defining layer 163 is formed on the transparent electrode 161, and the pixel defining layer 163 is patterned to expose a portion of the transparent electrode 161. The hole injection / transport layer 165 is formed on the exposed transparent electrode 161. In addition, the light emitting layer 173 is provided on the hole injection / transport layer 165.

The electron injection / transport layer 175 is formed on the emission layer 173, and the opposite electrode 177 is formed on the electron injection / transport layer 175. The counter electrode 177 is formed using Mg, Ca, Al, Ag, Ba, or an alloy thereof to reflect light generated by the light emitting layer 173.

The organic light emitting device described above has a bottom light emitting structure. In the case of the bottom emission, since an active circuit is interposed in one pixel, it is a disadvantage that the emission area is small. In addition, since the transistor, which is an active element, is formed on amorphous silicon or polycrystalline silicon, a change in threshold voltage is caused by continuous operation of the transistor.

In order to compensate for this, a circuit for compensating the threshold voltage may be interposed in the active circuit of the pixel, but this has the disadvantage of reducing the emission area.

In order to overcome this problem, the thickness of the counter electrode may be reduced, and a reflective film may be formed under the transparent electrode to form a top emission structure. However, the reduction of the thickness of the counter electrode may limit the supply of current required for the light emission operation. .

Therefore, in an active organic light emitting device, there will be a need for a new organic light emitting device that is substantially free of variations in the characteristics of transistors and that can transmit data signals to the light emitting layer.

An object of the present invention for solving the above problems is to provide an organic electroluminescent device for operating an organic electroluminescent device by configuring an active circuit on a single crystal silicon.

The present invention for achieving the above object, the organic light emitting device having a light emitting region and the pad connected to the light emitting region; And a pixel driving circuit formed on the single crystal silicon substrate, and configured to drive a pixel driving circuit for driving the organic light emitting diode, and electrically connected to a pad of the organic light emitting diode.

According to the present invention, the pixel driver may be formed on a single crystal silicon substrate separate from the substrate on which the organic light emitting diode is formed to maintain excellent electrical characteristics.

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

Example

2 is a circuit diagram illustrating a pixel circuit according to a preferred embodiment of the present invention.

Referring to FIG. 2, the pixel circuit includes a pixel driver 101 and an organic light emitting diode OLED. The pixel driver 101 has a switching transistor M1, a driving transistor M2, a light emitting transistor M3, and a capacitor C, each of which is formed on a single crystal silicon substrate.

When the scan signal SCAN [n] is applied at the low level, the switching transistor M1 is turned on, and the data signal DATA [m] is applied to the gate terminal of the capacitor C and the driving transistor M2. The driving transistor M2 generates the driving current Idr in accordance with the voltage difference between the source and the gate terminal. The voltage difference Vsg between the source and gate terminal of the driving transistor M2 is stored as the voltage difference across the capacitor C.

Subsequently, when the scan signal SCAN [n] changes to the high level and the emission control signal EMI [n] becomes the low level, the light emitting transistor M3 is turned on. By turning on the light emitting transistor M3, the driving transistor M2 generates the driving current Idr. When the driving current Idr is generated, the driving transistor M2 is preferably operated in the saturation region. The drive current Idr causes the organic electroluminescent element OLED to start emitting operation.

In addition, the pixel circuit according to the present invention does not include the light emitting transistor M3, and the driving transistor M2 and the organic light emitting diode OLED may be directly connected, or may be configured as a current write type.

In addition, although the pixel driver in FIG. 2 is illustrated as being composed of PMOS, the pixel driver may be configured of NMOS or CMOS, and may be formed of a bipolar transistor and a capacitor according to a semiconductor manufacturing process.

3 is a plan view illustrating a layout of the organic light emitting display device according to the preferred embodiment of the present invention.

Referring to FIG. 3, one pixel area 300 includes a light emitting area 310, a lower electrode line 312, an upper electrode line 314, a lower electrode pad 316, and an upper electrode pad 318.

An organic light emitting diode OLED is formed in the emission region 310. In addition, the lower electrode line 314 of the organic light emitting diode OLED extends to the lower electrode pad 316. The upper electrode line 314 of the organic light emitting diode OLED extends to the upper electrode pad 318. The lower electrode pad 312 and the upper electrode pad 318 are in contact with a bump of a semiconductor circuit formed by a semiconductor manufacturing process on a single crystal substrate.

The lower electrode line 312 and the upper electrode line 314 are made of a conductive material.

The lower electrode line 312 may be formed of the same material as the lower electrode material formed in the emission area, and the upper electrode line 314 may be formed of the same material as the upper electrode material formed in the emission area.

4A is a cross-sectional view when the pixel illustrated in FIG. 3 is cut along the line AA ′ according to the exemplary embodiment of the present invention.

Referring to FIG. 4A, a lower electrode 402 is formed on the substrate 400. The lower electrode 402 is a transparent electrode and is formed of an indium tin oxide (ITO) or an indium zinc oxide (IZO) film. A pixel definition layer 404 is formed on the lower electrode 402, the pixel definition layer 404 is patterned, and a pixel definition layer pattern exposing a portion of the lower electrode 402 is formed. An area exposed between the pixel defining layer patterns of the lower electrode 402 is defined as an opening area.

In addition, an organic functional film having at least the light emitting layer 408 is formed on the opening region. The hole injection / transport layer 406 may be formed on the opening area before the emission layer 408 is formed. In addition, after the emission layer 408 is formed, an electron injection / transport layer 410 may be formed in an upper region of the emission layer 408.

Subsequently, the counter electrode 412 is formed on the electron injection / transport layer 410. The counter electrode 412 is made of a conductive material that can reflect light. Accordingly, the counter electrode 412 is formed using Mg, Ca, Al, Ag, Ba or alloys thereof, but is formed to reflect light by adjusting the thickness thereof.

In addition, an insulating film 414 is formed on the counter electrode 412. The insulating film 414 serves to protect the organic functional film from external gas or moisture.

The lower electrode 406 is electrically connected to the lower electrode line 312 of FIG. 3, and the opposite electrode 412 is electrically connected to the upper electrode line 314 of FIG. 3. In addition, in FIG. 4A where the organic light emitting diode OLED is formed, the anode electrode of the organic light emitting diode OLED corresponds to the lower electrode 406, and the cathode electrode of the organic light emitting diode OLED corresponds to the opposite electrode 412.

4B is a cross-sectional view of the pixel of FIG. 3 taken along the line BB ′ according to an exemplary embodiment of the present invention.

Referring to FIG. 4B, a pixel defining layer pattern 404, an insulating layer 414, a lower electrode line 312, an upper electrode line 314, a lower electrode pad 316, and an upper electrode pad may be formed on the substrate 400. 318 is formed.

The pixel definition layer pattern 404 defines a region in which the organic functional layer is formed. The region where the electrode pads are formed is formed outside the light emitting region. Therefore, the outside of the emission area is entirely covered by the pixel definition layer pattern 404. In addition, according to the embodiment, instead of the pixel definition layer pattern 404, a separate film quality formed of an insulator may be formed.

A lower electrode line 312 is formed under the pixel definition layer 404. The lower electrode line 312 is a lower electrode formed in the light emitting region extending outside the light emitting region, and is electrically shorted with the lower electrode of the light emitting region. Preferably, the material forming the lower electrode line 312 is made of the same material as the lower electrode of the emission region.

In addition, an insulating film 414 is formed on the pixel definition layer pattern 404, and an upper electrode line 314 is formed under the insulating film 414. The upper electrode line 314 is electrically shorted with the opposite electrode of the emission area.

The lower electrode pad 316 is connected to the lower electrode line 312 through the pixel defining layer pattern 404 and the insulating layer 414. Electrical connection of the lower electrode pad 316 and the lower electrode line 312 is accomplished through a conventional lithography process.

That is, a photoresist is applied to a region where the lower electrode pad 316 is formed, patterned through exposure, and the lower electrode line 312 is exposed through etching. Subsequently, the lower electrode pad 316 may be formed by filling a conductor in a hole formed through etching.

In addition, the upper electrode pad 318 passes through the insulating layer 414 and is connected to the upper electrode line 314. Electrical connection of the upper electrode pad 318 and the upper electrode line 314 is accomplished through a conventional lithography process. That is, photoresist is applied to a region where the upper electrode pad 318 is formed, patterned through exposure, and the upper electrode line 314 is exposed through etching. Subsequently, the upper electrode pad 314 may be formed by filling a conductor in a hole formed through etching.

In FIG. 4B, the lower electrode line 312 and the upper electrode line 314 are formed by different layers, but the lower electrode line and the upper electrode line may be formed on the same layer.

5 is a cross-sectional view for describing the formation of the pixel driver of FIG. 2 on a single crystal silicon substrate according to a preferred embodiment of the present invention.

Referring to FIG. 5, trenches 502A and 502B for defining an active region are formed on the single crystal silicon substrate 500. The trenches 502A and 502B are made of an insulator, which is made of silicon oxide.

Transistors are formed in the active region defined by trenches 502A and 502B.

First, a dielectric film 504 is formed on an active region, and a conductive gate 506 is formed on the dielectric film 504. The conductive gate 506 is made of a conductor, preferably made of polycrystalline silicon. In addition, spacers 508 are formed along sidewalls of the dielectric film 504 and the conductive gate 506. In addition, a hard mask layer may be formed on the conductive gate 506 to protect the conductive gate 506 during the ion implantation process.

Subsequently, high concentration doped regions 510A and 510B are formed in the spaced space between the spacer 508 and the trenches 502A and 502B. Depending on the material to be doped, the transistor has a conductivity type of N or P type.

When the transistor is completed as described above, an insulating film (not shown) for completely filling the transistor is coated. The coated insulating film is patterned, and pads are formed on the surface of the insulating film to enable electrical connection with the outside.

Although only a process of forming one transistor is illustrated in FIG. 5, the pixel driver illustrated in FIG. 2 may be formed on a single crystal silicon substrate through a conventional semiconductor manufacturing process as described above. to be.

In addition, although not shown in FIG. 5, a bump is formed on the pad above the insulating film to achieve electrical contact with the outside. In addition, a plurality of transistors constituting the pixel driving circuit may be formed by different layers according to a semiconductor manufacturing process. In this case, the insulating film may be formed of a plurality of interlayer insulating films.

6 is a cross-sectional view showing the structure of an organic light emitting display device according to a preferred embodiment of the present invention.

Referring to FIG. 6, the semiconductor substrate illustrated in FIG. 5 is electrically coupled to the cross-sectional view illustrated in FIG. 4B. That is, the lower electrode pad and the upper electrode pad of the organic light emitting diode are electrically connected to the pixel driver on the single crystal silicon substrate formed according to FIG. 5. The electrical connection between the pixel driver and the organic light emitting display device is performed by bumps formed on the single crystal silicon substrate. The bump may be provided on the single crystal silicon substrate, but in some cases, the bump may be formed on the lower electrode pad and the upper electrode pad on which the organic light emitting diode is formed.

That is, the pixel driver of the active matrix organic light emitting display device is formed on a single crystal silicon substrate through a conventional semiconductor manufacturing process, and the organic light emitting device that performs light emission according to a data signal transmitted through the pixel driver is formed on a transparent substrate. Is formed.

In addition, electrical connection between the pixel driver and the organic light emitting diode is achieved through bumps. It is known to those skilled in the art that the threshold voltage of a transistor formed on a single crystal silicon substrate has no change in characteristics with respect to temperature or external influences. In addition, when the active circuits are formed on the single crystal silicon substrate, and the organic light emitting diode which emits light is formed on the transparent substrate, excellent light emission characteristics can be maintained.

According to the present invention as described above, the pixel driving unit for driving the organic light emitting device is formed on a separate semiconductor substrate, the organic light emitting device has a back light emitting structure while the anode electrode and the cathode electrode is a semiconductor in which the pixel driver is formed Is electrically connected to the substrate. Therefore, the degradation of the characteristics of the pixel driver can be prevented, and the organic light emitting diode can have a high light emitting area for one pixel.

Although described above with reference to a preferred embodiment of the present invention, those skilled in the art will be variously modified and changed within the scope of the invention without departing from the spirit and scope of the invention described in the claims below I can understand that you can.

Claims (5)

An organic light emitting display device having a light emitting area and a pad connected to the light emitting area; And And a pixel driver circuit formed on a single crystal silicon substrate and configured to drive a pixel driving circuit for driving the organic light emitting device, the pixel driver being electrically connected to a pad of the organic light emitting device. The organic light emitting device of claim 1, wherein the organic light emitting device has a bottom light emitting structure. The organic light emitting device of claim 2, wherein the pixel driver formed on the single crystal silicon substrate is connected to a pad of the organic light emitting diode through a bump. The organic light emitting device of claim 3, wherein the pixel driver is a current write type or a voltage write type. The method of claim 4, wherein the organic light emitting device, A light emitting area for performing a light emitting operation according to an applied data signal; A lower electrode line connected to the anode electrode of the organic light emitting device; A lower electrode pad electrically connected to the lower electrode line; An upper electrode line connected to the cathode of the organic light emitting diode; And And an upper electrode pad electrically connected to the upper electrode line.

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