JP2002149088A - Organic self-luminous display - Google Patents

Abstract

(57) [Problem] To provide an organic self-luminous display device capable of preventing breakage of electrodes and short circuit between electrodes beforehand. SOLUTION: A first thin film transistor arranged on a transparent substrate, a second thin film transistor controlled by the first thin film transistor, an anode connected to the second thin film transistor, an organic light emitting unit arranged on the anode, and an organic light emitting unit An organic self-luminous display device comprising: an organic EL element having a cathode disposed thereon; wherein the anode has a plurality of insulating films formed on the first and second thin film transistors through a stacked film of a plurality of insulating films. It is characterized by being connected to a second thin film transistor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an organic self-luminous display device.

[0002]

2. Description of the Related Art A display device using a light emitting diode, a liquid crystal, an organic EL (Electro Luminescence), or the like as a pixel,
Since the display portion can be made thinner, the range of application is not limited to display devices such as office equipment and computers, and the range of application tends to be further expanded. Among these displays, an organic self-luminous display using an organic EL is a liquid crystal display (LCD).
Has the advantages shown in the following items a to d.

A. Since it is a self-luminous type, a clear display and a wide viewing angle can be obtained, and further, a backlight is not required, so that the power consumption, weight, and thickness of the display device can be reduced. b. Since it is a DC constant voltage drive, it is strong against noise. c. The response speed is fast, for example, milliseconds (mse
c) On the order of microseconds (μsec) for organic self-luminous display devices, on the other hand. d. Since light is emitted by the solid layer, the operating temperature range may be widened.

[0004] Due to these advantages, their development is being actively pursued. In particular, research and development of a polycrystalline silicon TFT type organic self-luminous panel having an active matrix configuration capable of full color display in combination with a thin film transistor using polycrystalline silicon (hereinafter abbreviated as TFT) has been actively conducted. ing.

FIG. 4 is a vertical sectional view of a sub-pixel of a conventional organic self-luminous display device of this type, that is, a constant current TFT and a light-emitting portion of one color pixel constituting one pixel with three colors of R, G, and B. It is. In this organic self-luminous display device, a buffer layer 102 for preventing elution of mobile ions from a glass substrate is formed on a glass substrate 101. On this buffer layer 102, a polycrystalline silicon layer 103 is formed in an island shape corresponding to the TFT. This polycrystalline silicon layer 103 is partitioned into a source region, a carrier region, and a drain region. A gate oxide film 104 is formed on the entire surface of the buffer layer 102 including the polycrystalline silicon layer 103, and a gate electrode 106 is formed on the gate oxide film 104 corresponding to the carrier layer of the polycrystalline silicon layer 103. Further, a capacitor wiring 105 is formed in parallel with the gate line. Further, the capacitance wiring 105 and the gate electrode 106
An interlayer insulating film 107 for insulating metal wirings and the like is laminated on the gate oxide film 104 including. In the interlayer insulating film 107, a source electrode 108s and a drain electrode 108d respectively connected to portions corresponding to the source region and the drain region of the polycrystalline silicon layer 103 are penetrated. Further, an anode 109 made of a transparent electrode is formed on the interlayer insulating film 107 including the region where the capacitor wiring 105 is arranged, and one end of the anode 109 is connected to the drain electrode 108d.

In order to electrically insulate the anode 109 from the TFT between adjacent pixels, the anode 10
9, a passivation film 110 made of an inorganic material and a partition insulating film 1 made of an organic material covering the TFT formation region.
11 are formed. Thus, most of the surface of the anode 109 includes the passivation film 110 and the partition insulating film 11.
1, the hole transport layer 112, the hole injection layer 113, and the light emitting layer 11 which constitute the organic light emitting element together with the anode 109 on the partition insulating film 111 including the exposed surface.
4. The electron injection layer 115, the cathode buffer layer 116, and the cathode 117 are sequentially stacked.

Further, a glass substrate 119 is mounted on a surface portion separated from the cathode 117 in parallel with the glass substrate 101 on which the TFT is formed, and the periphery of these substrates is sealed with a sealing material 120. , Glass substrate 119
A drying agent 11 such as zeolite or BaO
8 is applied, and the inside is further filled with dry nitrogen.
Thus, an organic self-luminous panel is formed on the TFT substrate side, in which light is extracted and used as a display surface.

[0008]

In the conventional organic self-luminous display device shown in FIG.
09 is formed, but the surface state of the interlayer insulating film 107 has a relatively large step due to the capacitor wiring 105 and the gate electrode 106 of the TFT arranged on the back surface. As exemplified here, the anode 109, the hole transport layer 112, the hole injection layer 113, the light emitting layer 114, the electron injection layer 115, the cathode buffer layer 116, and the cathode 117 are sequentially stacked in a region where the capacitor wiring 105 is arranged. In this case, if there is a step in the underlayer, the thickness of this portion, that is, the portion A and the portion B becomes thin, so that the anode 109 itself is broken or the insulation between the anode 109 and the cathode 117 becomes insufficient and May be short-circuited.

Further, since the structure of the TFT formed on the basis of the polycrystalline silicon layer 103 is also complicated, this portion also has a complicated uneven surface. Therefore, there is a problem that a light emitting area is narrowed.

The present invention has been made to solve the above problems, and an object of the present invention is to provide an organic self-luminous display device capable of preventing breakage of electrodes and short circuit between electrodes. is there.

Another object of the present invention is to provide an organic self-luminous display device capable of efficiently extracting light while expanding a light-emitting region.

[0012]

The invention according to claim 1 is
A first thin film transistor disposed on a transparent substrate;
An organic EL element having a second thin film transistor controlled by the thin film transistor, an anode connected to the second thin film transistor, an organic light emitting unit arranged on the anode, and a cathode arranged on the organic light emitting unit. In the organic self-luminous display device described above, the anode is connected to the second thin film transistor via a stacked film of a plurality of insulating films formed on the first and second thin film transistors. .

According to a second aspect of the present invention, in the organic self-luminous display device according to the first aspect, the laminated film is a laminated film of insulating films having the same elements and different composition ratios.

According to a third aspect of the present invention, in the organic self-luminous display device according to the second aspect, the laminated film is formed by laminating a SiN1 film and a SiN1.3 film.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail. Passivation film 11 shown in FIG.
Numeral 0 is formed on the anode 109, the source electrode 108s and the drain electrode 108d of the TFT, and has a function of protecting functions of the TFT and the like. Therefore, by forming the passivation film 110 over the entire surface of the interlayer insulating film 107 shown in FIG. 4, only an extreme step due to wiring or the like in a region not overlapping with the organic light emitting element portion can be eliminated to some extent. However, since a passivation film is not formed below the organic light-emitting element portion, this is not a measure for preventing the above-described breakage of the electrodes or short-circuit between the electrodes. In order to eliminate a step due to wiring or the like, a passivation film having a thickness on the order of microns is required.

However, as shown in FIG.
After the interlayer insulating film 107 is formed on the gate oxide film 104 including the capacitor wiring 105, when a passivation film 110 on the order of microns is formed, the interlayer insulating film 107 is peeled off at the protruding portion of the interlayer insulating film 107, that is, at the top indicated by arrow C. Was found to occur. Therefore, as shown in FIG. 3B, a passivation film 110A is formed in a surface region of the interlayer insulating film 107 including the capacitor wiring 105 by using a material having excellent protection characteristics.
In the case where a flattening insulating film 110B is formed using a material having excellent flattening characteristics, even if the thickness of these layers is on the order of microns, peeling as shown in FIG. Did not occur. Further, it is considered that the passivation film 110 is not limited to two layers but may be three or more layers in terms of difficulty in peeling. In the case where a thickness equal to or more than a predetermined value is required in order to eliminate the step, peeling can be suppressed by laminating a plurality of films. Incidentally, good results were obtained when SiN1 was used as the passivation film 110A and SiN1.3 was used as the planarization insulating film 110B.

FIG. 1 is a schematic plan view showing an embodiment of an organic self-luminous display device according to the present invention, and FIG. 2 is a schematic vertical sectional view of a sub-pixel. The same elements as those described above are denoted by the same reference numerals.

In an organic self-luminous display device, an array substrate and an opposing substrate arranged opposite to the array substrate are hermetically sealed inside via a sealing material.

As shown in FIG. 1, the array substrate is composed of a signal line 161 disposed substantially in parallel at equal intervals on a transparent insulating substrate such as glass, and a signal line 161 substantially orthogonal to the signal line 161 via an interlayer insulating film. Gate line 152 that is electrically insulated
A pixel TFT 21 disposed at each intersection thereof; a constant current supply TFT 22 having an output terminal connected to the gate electrode of the pixel TFT 21; a common line 151 connected to the source of the constant current supply TFT 22; Current supply TFT
And an organic light-emitting element unit 10 connected to the drain 22.

As shown in FIG. 2, the anode 109 forming the organic light emitting element portion, each wiring and the TFT are formed by a flattening insulating film 110A having excellent flattening characteristics and a passivation film 110B having excellent protection characteristics. It is electrically insulated by lamination.

As described above, since the laminated film of the planarizing insulating film and the passivation film is arranged on the multi-wiring and the TFT,
The surface of the passivation film 110B is flattened, and the anode 109 can be formed so as to extend to the constant current supply TFT, so that the light emitting region can be enlarged. Further, since these are formed by a laminated film, the film peeling can be suppressed as compared with a case where the same film thickness is formed by a single layer film.

In this case, since the flattening insulating film 110A and the passivation 110B are combined to have a thickness on the order of microns, a deep bottom is formed in a region where the anode 109 is connected to the drain electrode 108d. The depression may cause inconvenience in the formation of the multi-layered film constituting the organic light emitting element. Therefore, the partition insulating film 121 is provided also in this depression, so that a step on the drain electrode 108d of the constant current supply TFT can be reduced.

According to this configuration, since the surface of the passivation film 110B is flattened, it is possible to prevent breakage of the electrodes and short-circuit between the electrodes, and at the same time, enlarge the light emitting region.

Next, a method of manufacturing the organic self-luminous display device according to the present embodiment will be described with reference to FIGS.

First, a glass substrate 101 as a transparent insulating substrate is prepared, and on this glass substrate 101, for example,
100 nm thick SiNx and 150 nm thick SiOx
Are formed to form a buffer layer 102, and subsequently,
On the buffer layer 102, for example, a 50-nm-thick polycrystalline silicon film is formed, and the polycrystalline silicon film is patterned to form a polycrystalline silicon layer 103 region corresponding to the TFT.

Next, over the entire surface of the buffer layer 102 including the polycrystalline silicon layer 103, for example,
A gate oxide film 104 of m.m. SiOx is deposited, a 300 nm-thick MoW film is deposited on the gate oxide film 104, and the gate electrodes of the pixel TFT and the constant current TFT, and the A gate line and a capacitor wiring 105 which are formed integrally with the gate electrode are formed.

Next, a source region and a drain region are formed in the polycrystalline silicon layer by performing ion implantation from above using the resist at the time of forming the gate electrode as a mask.

Next, an interlayer insulating film 107 made of, for example, SiOx having a thickness of 600 nm is formed so as to cover all of these upper surfaces by CVD or the like, and then penetrates the interlayer insulating film and the gate oxide film. After a contact hole reaching the source region and the drain region is provided, a metal film, for example, Mo having a thickness of 50 nm, Al having a thickness of 450 nm, and Mo having a thickness of 100 nm are sequentially laminated and etched to form a source electrode 108s , A drain electrode 108d, a signal line, and a common wiring are formed.

Further, a passivation film 110A made of, for example, SiNx is formed to a thickness of 450 nm on the entire surface of the substrate, and a flattening insulating film 110B made of SiNx is formed on the substrate.
A film is formed to a thickness of 00 nm. When SiN1 is used as the passivation film 110A, the planarization insulating film 1
SiN1.3 is used as 10B. That is, substances having the same elements but different composition ratios are stacked in two layers. Subsequently, a hole is made in the portion of the drain electrode of the constant current TFT.

Next, on the surface of the planarizing insulating film 110B including the holes formed simultaneously in the passivation film 110A and the planarizing insulating film 110B, for example, a 50 nm ITO (In)
An anode 109 made of dium Tin Oxide is formed and connected to the drain electrode 108d of the constant current TFT through a hole. In this case, the flattening insulating film 110B is laminated on the passivation film 110A, and the surface of the flattening insulating film 110B is flatter than the conventional device.
It is formed in a wider area than the conventional device, including an area corresponding to the polycrystalline silicon layer 103 where the FT is formed.

Next, a partition insulating film 111 is formed on the outside including the end of the anode 109, and the partition insulating film 121 is formed in a recess at a position where the anode 109 is connected to the drain electrode 108d.
Embed

Next, the exposed surface of the anode 109 and the partition insulating film 1
After the hole transport layer 112 and the hole injection layer 113 are laminated on the entire surface including the insulating film 11 and the partition insulating film 121, the light emitting layer 114 is formed in a region substantially corresponding to the anode 109. Further, the electron injection layer 1 is provided on the surface including the light emitting layer 114.
15, the cathode buffer layer 116 and the cathode 117 are sequentially laminated. Thus, an organic self-luminous panel is formed.

Next, the organic self-luminous panel and the glass substrate 119 coated with a desiccant 118 such as zeolite or BaO on the inner surface are sandwiched by a sealing member 120 at the side end of the organic self-luminous panel. Te, paste while sealed N ₂ therein.

According to this embodiment, each wiring and TFT
A flattening insulating film 110B made of a material having excellent flatness is laminated on the surface of the passivation film 110A where a large step is formed due to, for example, forming a thick protective film while maintaining the adhesion. Since the anode 109 is formed on the film 110B, breakage of the anode 109 itself and short circuit between the anode 109 and the cathode 117 can be prevented. In addition, since the anode 109 and the light-emitting layer 114 can be formed over the flattened insulating film 110B so as to overlap with the formation regions of the TFT and the capacitor, light can be extracted from a wide region.

In the above embodiment, the film thickness is 450 n
m on the passivation film 110A
Although the planarizing insulating film 110B made of the organic material m was formed, even if the planarizing insulating film 110B was set to 1000 nm, the film did not peel off as shown in FIG. This is considered to be an effect obtained by using substances having the same element but different composition ratios as materials for forming the passivation film 110A and the planarization insulating film 110B. As described above, when the thickness of the planarization insulating film 110B is increased, the effects of preventing breakage of electrodes and short circuit between electrodes, enlargement of a light emitting region, and efficient extraction of light can be further enhanced. .

The above-mentioned organic self-luminous panel, display is achieved by periodically arranging three pixels of R, G, and B on the glass substrate 101 and arranging a large number of sub-pixels in a matrix. Area. An X-driver external signal supply circuit and an X-driver are arranged at an outer end of one side of the display area, and a Y-driver external signal supply circuit and a Y-driver are arranged at an outer end of another adjacent side. Then, a signal line commonly connected to the pixels arranged in a column is connected to the X-driver, and a common line (VDD line) and a gate line commonly connected to pixels orthogonal to these are connected to the X-driver.
-Connected to the driver.

In the above-described embodiment, the organic self-luminous display device having the two-layered protective insulating film formed by laminating the planarizing insulating film 110B on the passivation film 110A has been described. The same effect can be obtained by laminating two or more layers of the planarizing insulating film on the passivation film 110A.

[0038]

As is apparent from the above description, according to the present invention, an organic self-luminous display device capable of preventing breakage of electrodes and short circuit between electrodes can be obtained.

Further, an organic self-luminous display device capable of expanding a light emitting region can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic plan view of an organic self-luminous display device of the present invention.

FIG. 2 is a schematic vertical sectional view of a sub-pixel for describing a configuration of an embodiment of an organic self-luminous display device according to the present invention.

FIG. 3 is a longitudinal sectional view of a passivation film laminated on a wiring for explaining the principle of the present invention.

FIG. 4 is a longitudinal sectional view of a sub-pixel of a conventional organic self-luminous display device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 EL element 21 Pixel TFT 22 Constant current supply TFT 101 Glass substrate 103 Polycrystalline silicon layer 105 Capacitance wiring 106 Gate electrode 107 Interlayer insulating film 108s Source electrode 108d Drain electrode 109 Anode 110A Passivation film 110B Flattening insulating film 111 Partition insulating film 114 Light emitting layer 117 Cathode 119 Transparent insulating substrate 120 Sealant

Claims (3)

[Claims] A first thin film transistor disposed on a transparent substrate; a second thin film transistor controlled by the first thin film transistor; an anode connected to the second thin film transistor; and an organic light emitting element disposed on the anode. And an organic EL element having a cathode disposed on the organic light-emitting unit. An organic self-luminous display device comprising: a plurality of anodes formed on the first and second thin film transistors; An organic light emitting display device connected to the second thin film transistor via a laminated film of the insulating film. 2. The organic self-luminous display device according to claim 1, wherein said laminated film is a laminated film of insulating films having the same element and different composition ratios. 3. The organic self-luminous display device according to claim 2, wherein said laminated film is formed by laminating a SiN1 film and a SiN1.3 film.