JP2002033198A - Light emitting device and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bright light emitting device with good image quality. SOLUTION: An EL element 105 consisting of an electrode 102 containing a reflecting surface, an organic EL layer 103 and a transparent electrode 104 is provided on an insulator 101, and an auxiliary electrode 107 is connected to the transparent electrode 104 through an anisotropic conductor 108. Accordingly, since the effective resistance value of the transparent electrode 104 can be reduced, and a uniform voltage can be applied to the organic EL layer 103, a display failure such as display unevenness or the like can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting device using a thin film made of a light emitting material. Further, the present invention relates to an electric appliance using the light emitting device as a display portion. In addition, organic E
L displays and organic light emitting diodes (OLED: Orga
nic Light Emitting Diode) is included in the light emitting device of the present invention.

[0002] The luminescent material that can be used in the present invention includes all luminescent materials that emit light (phosphorescence and / or fluorescence) via singlet excitation, triplet excitation, or both.

[0003]

2. Description of the Related Art In recent years, a light-emitting element (hereinafter, referred to as an EL element) using a thin film (hereinafter, referred to as an EL film) made of a light-emitting material capable of obtaining EL (Electro Luminescence) has been developed. A light emitting device having an EL element (hereinafter referred to as EL
A light-emitting device) has an EL element having a structure in which an EL film is interposed between an anode and a cathode, and emits light by applying a voltage between the anode and the cathode. In particular, a film using an organic film as the EL film is called an organic EL film.

As the cathode, a metal having a small work function (typically, a metal belonging to Group 1 or 2 of the periodic table) is often used, and as the anode, a conductive film transparent to visible light (hereinafter, transparent). (Referred to as a conductive film) in many cases. Due to such a structure, the obtained light emission is visually recognized through the anode.

Recently, an active matrix type EL light emitting device that controls light emission of an EL element provided in each pixel using a TFT (thin film transistor) has been developed, and a prototype has been announced. Here, the structure of the active matrix EL light emitting device is shown in FIGS. 9A and 9B.
Shown in

Referring to FIG. 9A, a T
An FT 902 is formed, and an anode 903 is connected to the TFT 902. On the anode 903, an organic EL film 90
4. A cathode 905 is formed, an anode 903, an organic EL film 9
An EL element 906 composed of an element 04 and a cathode 905 is formed.

At this time, the light emitted from the organic EL film 904 passes through the anode 903 and is emitted in the direction of the arrow in the figure. Accordingly, the TFT 902 becomes a shield that blocks light emission when viewed from the observer, and is a factor that narrows the effective light emitting area (the area where the observer can observe light emission). In addition, when the effective light emitting area is small, it was necessary to increase the light emission luminance in order to obtain a bright image. However, increasing the light emission luminance hastened the deterioration of the organic EL film.

Therefore, an active matrix EL light emitting device having a structure as shown in FIG. 9B has been proposed.
In FIG. 9B, a TFT 902 is formed over a substrate 901, and a cathode 907 is connected to the TFT 902. On the cathode 907, an organic EL film 908 and an anode 909
Are formed, and an EL element 910 including a cathode 907, an organic EL film 908, and an anode 909 is formed. That is, the EL element has a structure exactly opposite to that of the EL element 906 shown in FIG.

At this time, in principle, light emitted from the EL film 908 passes through the anode 909 and is emitted in the direction of the arrow in the figure. Therefore, the TFT 901 is provided at a position invisible to an observer, and the entire area where the cathode 903 is provided can be used as an effective light emitting area.

[0010] However, the structure shown in FIG.
There is a potential problem that a uniform voltage cannot be applied to the anode 909. Although a transparent conductive film generally used as an anode has a higher resistance value than a metal film, it is known that the resistance value can be reduced by heat treatment. However, since the heat resistance of the organic EL film is low, it is impossible to perform a heat treatment at more than 150 ° C. after forming the organic EL film.

Therefore, when stacking an anode (transparent conductive film) on the organic EL film, heat treatment cannot be performed, and it is difficult to form an anode having a low resistance value. That is, there is a possibility that a problem occurs in that the voltage applied between the end portion and the center portion of the anode is different, and there is a concern that this problem may cause image quality failure.

As described above, the light emitting device including the structure using the transparent conductive film after forming the organic EL film has a problem that it is difficult to reduce the resistance of the transparent conductive film.

[0013]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a light emitting device which is bright and has good image quality. Another object is to provide an electric appliance with high image quality using such a light-emitting device as a display portion.

[0014]

According to the present invention, a transparent electrode provided after forming an organic EL film is connected in parallel with an auxiliary electrode to substantially reduce the resistance of the transparent electrode. There is a feature in the point of aiming. Here, the present invention will be described with reference to FIG.

In FIG. 1, 101 is an insulator, 102 is an electrode including a reflection surface, 103 is an organic EL layer, 104 is an electrode transparent or translucent to visible light (hereinafter referred to as a transparent electrode). An EL element 105 including an electrode 102 including a reflective surface, an organic EL layer 103, and a transparent electrode 104 is formed on the body 101.

The term "transparent to visible light" means that visible light is
Transmitting light with a transmittance of 0 to 100% means translucent to visible light means transmitting visible light with a transmittance of 50 to 80%. Of course, the transmittance varies depending on the film thickness, but the film thickness may be appropriately designed so as to fall within the above range.

Here, the insulator 101 is an insulating substrate or a substrate provided with an insulating film on the surface, and may be any as long as it can support an EL element.

The electrode 102 including the reflection surface refers to a metal electrode or an electrode in which a metal electrode and a transparent electrode are stacked. That is, it refers to an electrode including a surface (reflection surface) that can reflect visible light on the front surface, the back surface, or the interface inside the electrode.

As the organic EL layer 103, an organic EL film or a laminated film of an organic EL film and an organic material can be used. That is, the organic EL film may be provided as a single layer as a light emitting layer, or the organic EL film may be provided as a light emitting layer and an organic material may be stacked as a charge injection layer or a charge transport layer. Note that some of the inorganic materials can be used as the charge injection layer or the charge transport layer, and such an inorganic material can be used as the charge injection layer or the charge transport layer.

As the transparent electrode 104, an electrode made of a transparent conductive film or an electrode made of a metal film having a thickness of 5 to 70 nm (typically 10 to 50 nm) (hereinafter, referred to as a semi-transparent metal film) is used. Can be used. As the transparent conductive film, an oxide conductive film (typically, an indium oxide film, a tin oxide film, a zinc oxide film, a compound film of indium oxide and tin oxide or a compound film of indium oxide and zinc oxide) or an oxide film A conductive film to which gallium oxide is added can be used. In the case where a transparent conductive film is used as the transparent electrode 104, visible light of 80 to 95% can be transmitted by setting the thickness to 10 to 200 nm (preferably 50 to 100 nm).

On the EL element 105 having the above structure, a sealing member 106 and an auxiliary electrode 107 provided on the surface of the sealing member 106 are provided.
8 and is electrically connected to the transparent electrode 104.
Note that the conductors 108 are provided scattered over the transparent electrode 104, but it is preferable that the conductors 108 be provided as dispersed over the entire surface of the transparent electrode as much as possible.

Here, the sealing body 106 is a substrate or a film transparent to visible light, and a glass substrate, a quartz substrate, a crystallized glass substrate, a plastic substrate or a plastic film can be used. However, when a plastic substrate or a plastic film is used, it is desirable to provide a protective film (preferably a carbon film, specifically, a diamond-like carbon film) on the front surface or the back surface for preventing oxygen and water from permeating.

The auxiliary electrode 107 is an auxiliary electrode provided for the purpose of lowering the resistance of the transparent electrode 104.
Similarly to the transparent electrode 104, an electrode made of a transparent conductive film or an electrode made of a translucent metal film can be used. Further, the film thickness of the auxiliary electrode 107 is set to 10 to 200 nm (preferably 50 to 100 nm) similarly to the transparent electrode 104.
By setting m), 80 to 95% of visible light can be transmitted.

The conductor 108 can be formed using a conductive film called an anisotropic conductive film or the like. Therefore,
It can also be called an anisotropic conductive film. The anisotropic conductive film is a resin film in which conductive particles (typically, metal particles or carbon particles) are uniformly dispersed. In the present invention, it is preferable that the anisotropic conductive film 108 is selectively formed by patterning by photolithography or selectively formed by an inkjet method or a printing method. This is because the anisotropic conductive film has low transmittance to visible light,
This is because, if provided on the entire surface of No. 4, light emitted from the organic EL layer 103 will be absorbed.

In the light emitting device of the present invention having the above-described structure, the auxiliary electrode 107 is made of a transparent electrode 1 made of a transparent conductive film.
It functions as an electrode connected in parallel with the element 04. Further, at this time, since the auxiliary electrode 107 is formed on the sealing body 106 side, the resistance value can be reduced without being restricted by the heat resistance of the organic EL film as described in the conventional example. Therefore, by implementing the present invention, it is possible to apply a uniform voltage to the transparent electrode 104, and it is possible to obtain a high quality image.

[0026]

FIG. 2 shows an embodiment of the present invention.
This will be described with reference to FIG. In FIG. 2, reference numeral 201 denotes a substrate on which an element is formed. In the present invention, any material may be used for the substrate 201, such as glass (including quartz glass), crystallized glass, single crystal silicon, ceramics,
Metal or plastic can be used.

Pixels 202 are formed on a substrate 201,
The pixel 202 includes a switching TFT 203 and a current control T
The structure includes the FT 204. FIG. 2 shows three pixels, each of which has a pixel that emits red, green, or blue light. Switching TFT 203
Functions as a switch for capturing a video signal into a pixel, and the current control TFT 204 functions as a switch for controlling the current flowing through the EL element. At this time, the drain of the switching TFT 203 is connected to the current control TFT 2
04 is electrically connected to the gate.

Switching TFT 203 and current control T
The structure of the FT 204 is not limited, and a top gate type (typically, a planar type) or a bottom gate type (typically, an inverted stagger type) may be used. Also, which TFT
Also, an n-channel TFT or a p-channel TFT may be used.

The switching TFT 203 and the current control TFT 204 are covered with an interlayer insulating film 205, on which a pixel electrode 207 made of a metal film and a drain of the current control TFT 204 are electrically connected via a conductor plug 206. Have been. The pixel electrode 207 has a first transparent electrode 208 of 10 to 200 nm (preferably 50 to 1 nm).
(00 nm). Here, the anode 230 is formed by the pixel electrode 207 and the first transparent electrode 208.

In this embodiment, the current control TFT 2
The structure is such that a contact hole for connecting the drain electrode 04 and the pixel electrode 207 is filled with a conductor. The conductor provided to fill the contact hole is called a conductor plug. The conductor plug 206 may be formed by etching an anisotropic conductive film. Of course, the pixel electrode 20
7 may be directly connected to the drain of the current control TFT 204.

Incidentally, the concave portion caused by the contact hole is not preferable because the coverage of the organic EL layer is poor and a short circuit between the cathode and the anode may be caused. In this embodiment mode, by using the conductor plug 206, a concave portion due to a contact hole can be prevented from being formed in the pixel electrode 207, so that a short circuit between the cathode and the anode can be prevented.

The pixel electrode 207 is preferably formed of a metal film having high reflectance, and is preferably formed of an aluminum film (including an aluminum alloy film and an aluminum film containing an additive) or a silver thin film. A film in which a metal film is plated with aluminum or silver may be used.

Next, reference numeral 209 denotes an insulating film (hereinafter referred to as a bank) provided between the anodes 230, and is formed so as to cover a step formed at an end of the anode 230. In this embodiment mode, the bank 209 is provided to keep the organic EL layer away from the end of the anode 230 where electric field concentration is likely to occur, thereby preventing the organic EL layer from being deteriorated due to electric field concentration. Note that as the bank 209, a resin film or an insulating film containing silicon (typically, a silicon oxide film) may be used.

An organic EL 210 emits red light.
Layer 211 is an organic EL layer emitting green light, and 212 is an organic EL layer emitting blue light. Organic EL layers 210 to 21
The layer structure of 2 may refer to a known technique.

The second transparent electrode 213 provided so as to cover the organic EL layers 210 to 212 is an electrode for injecting electrons into the organic EL layers. The work function of the second transparent electrode 213 is preferably 2.5 to 3.5 eV, and a metal film containing an element belonging to Group 1 or 2 of the periodic table may be used. Here, an alloy film in which aluminum and lithium are co-evaporated (hereinafter, referred to as an Al-Li film) is used. Further, since the Al—Li film is a metal film, the thickness is 10 to 70 nm (typically, 20 to 50 nm).
By setting m), a transparent electrode can be obtained.

Further, 100 to 300 nm
A third transparent electrode 214 (preferably 150 to 200 nm) made of a transparent conductive film is provided. The third transparent electrode 214 is an electrode that serves to apply a voltage to the second transparent electrode 213. Here, the second transparent electrode 2
13 and the third transparent electrode 214 form a cathode 231.

The sealing member 215 provided to face the substrate 201 (herein, the substrate including the thin film provided on the substrate 201) has a thickness of 10 to 200 nm.
An auxiliary electrode (fourth transparent electrode) 216 made of a transparent conductive film (preferably 50 to 100 nm) is formed.
The third transparent electrode 214 and the auxiliary electrode 216 are electrically connected via a conductor 217 made of an anisotropic conductive film (a resin film in which metal particles or carbon particles are dispersed).

It is preferable that the conductor 217 be provided partially on the third transparent electrode 214. That is, since the anisotropic conductive film is black or gray, it is preferable that the anisotropic conductive film be provided so as not to overlap at least the light emitting region of the pixel. Of course, it is also possible to increase the directivity of light for each pixel by using it as a black matrix by providing it between pixels.

The substrate 201 and the sealing body 215 are bonded to each other by a sealing material (not shown) provided on the outer edge of the substrate 201. When the substrate 201 and the sealing body 215 are attached to each other, the substrate 201 and the sealing body 215 are bonded together.
Spacers (preferably 1 to 3 μm)
m) may be provided. In particular, this spacer is
7 is effective.

The substrate 201 and the sealing body (counter substrate) 2
It is preferable that a nitrogen gas or a rare gas is sealed in the space 218 formed between the space 218 and the space 218. Further, it is desirable to provide a substance having a hygroscopic property or a substance having a deoxidizing property in the space 218.

Here, the detailed structure of the region 219 is shown in FIG.
It is shown in (B). In FIG. 2B, the anode 230, the organic EL layer 212, and the cathode 231 form the EL element 220. The most characteristic point of the light emitting device shown in FIG. 2A is that light emission is observed through the cathode 231.

Of the light generated by the EL element 220, the light directed toward the anode 230 is reflected by the pixel electrode 207 having a highly reflective surface, and directed toward the cathode 231. That is, the pixel electrode 207 is an electrode that supplies a current to the anode 230 (extracts electrons) and also has a function as a reflective electrode.

Since the second transparent electrode 213 has a very small thickness, it has a high resistance value. Therefore, the third transparent electrode 21
4 to reduce the resistance. However, the transparent conductive film used as the third transparent electrode 214 is an organic EL
Since the layer 212 is formed after being formed, it is difficult to reduce the resistance value. Therefore, in the present embodiment, in parallel with the third transparent electrode 214 made of a transparent conductive film,
By connecting the auxiliary electrode 216 made of a transparent conductive film, the resistance of the third transparent electrode 214 is substantially reduced.

The light emitting device having the above-described structure has the pixel 20
Since the entire area 2 is an effective light emitting area, a very bright image can be obtained. In addition, by applying the present invention, a uniform voltage can be applied to the entire cathode 231, so that a high-quality image can be obtained.

[0045]

[Embodiment 1] In this embodiment, a manufacturing process of the light emitting device shown in FIG. 2 will be described with reference to FIGS. Note that FIGS. 3 and 4 are cross-sectional views illustrating a manufacturing process in the pixel portion. FIG. 5A shows a top view of a pixel manufactured according to this embodiment (however, a top view when an anode is formed), and FIG. 5B shows a circuit diagram of a final pixel. The reference numerals used in FIG. 5 correspond to the reference numerals used in FIGS.

First, as shown in FIG. 3A, a glass substrate 301 is prepared as a substrate, and a base film 302 made of a silicon oxide film is formed thereon to a thickness of 200 nm. The base film 302 is formed by a low pressure thermal CVD method, a plasma CVD method,
A sputtering method or an evaporation method may be used.

Next, the crystalline silicon film 3
03 is formed to a thickness of 50 nm. Crystalline silicon film 303
A known method can be used as a method for forming the film. The amorphous silicon film may be laser-crystallized using a solid-state laser or excimer laser, or the amorphous silicon film may be crystallized by heat treatment (furnace annealing). In this embodiment, crystallization is performed by excimer laser irradiation using XeCl gas.

Next, as shown in FIG. 3B, the crystalline silicon film 303 is patterned to form an island-like crystalline silicon film 30.
4, 305 are formed. Then, the island-shaped crystalline silicon film 30
4, a gate insulating film 3 made of a silicon oxide film covering 305
06 is formed to a thickness of 80 nm. Further, gate electrodes 307 and 308 are formed on the gate insulating film 306.
Although two gate electrodes 307 appear in the drawing, they are actually the same electrode that is bifurcated.

In this embodiment, the gate electrodes 307, 3
As a material 08, a 350 nm-thick tungsten film or a tungsten alloy film is used. Of course, other known materials can be used as the material of the gate electrode. Further, in this embodiment, the connection wiring 309 is also formed at this time. The connection wiring 309 is a wiring for electrically connecting the source of the current control TFT and the current supply line later.

Next, as shown in FIG. 3C, an element belonging to Group 13 of the periodic table (typically, boron) is added using the gate electrodes 307 and 308 as a mask. A known method may be used for the addition method. Thus, an impurity region exhibiting a p-type conductivity (hereinafter referred to as a p-type impurity region) 310 to 3
14 are formed. Further, channel formation regions 315a, 315b, and 316 are defined immediately below the gate electrode. Note that the p-type impurity regions 310 to 314 serve as a source region or a drain region of the TFT.

Next, a heat treatment is performed to activate the added elements belonging to Group 13 of the periodic table. The pattern formed of the island-shaped crystalline silicon film performed up to the activation step is called an active layer. This activation is performed by furnace annealing, laser annealing or lamp annealing,
Alternatively, they may be performed in combination. In this embodiment, 5
Heat treatment at 00 ° C. for 4 hours is performed in a nitrogen atmosphere.

However, in this activation step, it is desirable that the oxygen concentration in the processing atmosphere be 1 ppm or less (preferably 0.1 ppm or less). This is because if the oxygen concentration is high, the surfaces of the gate electrodes 307 and 308 and the connection wiring 309 are oxidized, which makes it difficult to make electrical contact with a gate wiring or a current supply line to be formed later.

After the activation is completed, it is effective to perform a hydrogenation treatment. The hydrogenation treatment may use a known hydrogen annealing technique or a plasma hydrogenation technique.

Next, as shown in FIG. 3D, a current supply line 317 is formed so as to be in contact with the connection wiring 309. With such a structure (the top view is in a region denoted by 501 in FIG. 5A), the connection wiring 309 and the current supply line 317 are electrically connected. Although not shown, a gate wiring (a wiring indicated by 502 in FIG. 5A) is also formed at this time and is electrically connected to the gate electrode 307. This top view is shown in a region indicated by 503 in FIG.

In the region denoted by reference numeral 503, the reason why the gate wiring 502 has a projection is that the gate electrode 307
This is a redundant design to secure a part that does not survive. By doing so, the gate wiring 502 is connected to the gate electrode 30.
Even if the wire breaks at the part that goes over 7, the gate wiring 50
2 can be prevented from being electrically disconnected there. The processing of the gate electrode 307 in a U-shape is also a redundant design to ensure that a voltage is applied to both gate electrodes.

The current supply line 317 and the gate wiring 50
2 is formed of a metal film having lower resistance than the connection wiring 309 and the gate electrode 307. It is preferable to use a metal film containing aluminum, copper, or silver. That is, a metal film having high workability is used for a gate electrode requiring fine pattern accuracy, and a low resistance is used for a bus line (gate wiring and current supply line in this embodiment) requiring low resistivity. Use a suitable metal film.

After gate wiring 502 and current supply line 317 are formed, first interlayer insulating film 318 made of a silicon oxide film is formed.
Is formed to a thickness of 800 nm. As a forming method, a plasma CVD method may be used. As the first interlayer insulating film 318, another inorganic insulating film may be used, or a resin (organic insulating film) may be used.

Next, as shown in FIG. 3E, a contact hole is formed in the first interlayer insulating film 318 to form a wiring 319.
To 322. In this embodiment, the wirings 319 to 322 are used.
A metal wiring having a three-layer structure of titanium / aluminum / titanium is used. Of course, any material may be used as long as it is a conductive film. The wirings 319 to 322 serve as a source wiring or a drain wiring of the TFT.

The drain wiring 32 of the current control TFT
2 is electrically connected to the connection wiring 309. as a result,
The drain of the current control TFT 402 and the current supply line 317 are electrically connected.

In this state, the switching TFT 401 and the current control TFT 402 are completed. In this embodiment, both TFTs are formed of p-channel TFTs, but both or one of them may be an n-channel TFT.

The switching TFT 401 is formed such that the gate electrode crosses the active layer at two places.
It has a structure in which two channel forming regions are connected in series. With such a structure, the off-current value (TF
Current flowing when T is turned off) can be effectively suppressed.

A storage capacitor 504 is formed in the pixel as shown in FIG. FIG. 6 is a cross-sectional view of the storage capacitor 504 (a cross-sectional view taken along line BB ′ in FIG. 5A). The storage capacitor 504 includes the semiconductor layer 505 electrically connected to the drain of the current control TFT 402, the gate insulating film 3
06 and the capacitor wiring 506. That is, the semiconductor layer 505 and the capacitor wiring 506 are insulated by the gate insulating film 306 to form a capacitor (holding capacitor).

The capacitance wiring 506 is formed at the same time as the gate wiring 502 and the current supply line 317, and also serves as a wiring for electrically connecting the gate electrode 308 and the connection wiring 507. Note that the connection wiring 507 is a drain wiring (which may function as a source wiring) 32 of the switching TFT 401.
0 is electrically connected.

The advantage of the storage capacitor shown in this embodiment is that the capacitor wiring 506 is formed after forming the active layer.
That is, in the case of this embodiment, since the semiconductor layer 505 is a p-type impurity region, it can be used as it is as an electrode.

After forming the wirings 319 to 322, a passivation film 323 made of a silicon nitride film or a silicon nitride oxide film is formed to a thickness of 200 nm. By performing the hydrogenation treatment before or after the formation of the passivation film 323, the electrical characteristics of the TFT can be improved.

Next, as shown in FIG. 4A, an acrylic resin is formed as a second interlayer insulating film 324 to a thickness of 1 μm, a contact hole 325 is formed, and then an anisotropic conductive film 326 is formed. I do. In this embodiment, an acrylic resin in which silver particles are dispersed is used as the anisotropic conductive film 326. Also,
It is preferable that the anisotropic conductive film 326 be formed with a sufficient thickness so that the contact hole 325 can be flattened. In the present embodiment, it is formed by a spin coating method with a thickness of 1.5 μm.

Next, the anisotropic conductive film 326 is etched by plasma using oxygen gas. This process is continued until the second interlayer insulating film 324 is exposed. When the etching is completed, the conductor plug 327 is formed in a shape as shown in FIG. The second
When the interlayer insulating film 324 is exposed, the conductive plug 327 may have a step due to a difference in etching rate with the second interlayer insulating film 324. However, if the step is 100 nm or less (preferably 50 nm or less), there is a particular problem. Does not.

After the formation of the conductor plug 327, an aluminum film to which scandium or titanium is added and I
A pixel electrode 328 made of an aluminum film to which a TO film (a compound film of indium oxide and tin oxide) is laminated and etched to add scandium or titanium, and IT
A first transparent electrode 329 made of an O film is formed. In this embodiment, the pixel electrode 328 and the first transparent electrode 329 form an anode 340.

In this embodiment, the thickness of the aluminum film is 2
00 nm, and the thickness of the ITO film is 100 nm. The ITO film is made of ITO-04N (Ito of Kanto Chemical Co., Ltd.).
The aluminum film can be etched by a dry etching method using a mixed gas of carbon tetrachloride (SiCl ₄ ) and chlorine (Cl ₂ ).

The cross-sectional structure of FIG. 4B obtained in this way corresponds to the cross-sectional structure cut along the line AA ′ in FIG.

Next, as shown in FIG. 4C, an insulating film 330 is formed as a bank. In this embodiment, the bank 330 is formed using an acrylic resin, but it is also possible to form the bank 330 using a silicon oxide film. After the bank 330 is formed, the first transparent electrode 329 is irradiated with ultraviolet light in an oxygen atmosphere to perform a surface treatment on the first transparent electrode 329.
This has the effect of increasing the work function of the first transparent electrode 329 and also has the effect of removing surface contamination.

Then, each of the organic EL films 331 and 332 is formed to a thickness of 50 nm. Note that the organic EL film 331 is an organic EL film that emits blue light, and the organic EL film 332 is an organic EL film that emits red light. Although not shown, an organic EL film which emits green light at the same time is also formed. In this embodiment, an organic EL film is separately formed for each pixel by an evaporation method using a shadow mask. Of course, it is also possible to make them separately using a printing method or an ink jet method.

In this embodiment, the organic EL films 331, 3
Although an example in which 32 is used as a single layer is shown, a stacked structure using CuPc (copper phthalocyanine) as the hole injection layer is also effective. In this case, first, a copper phthalocyanine film is formed on the entire surface, and thereafter, an organic EL film that emits red light, an organic EL film that emits green light, and an organic EL film that emits blue light are respectively provided for pixels corresponding to red, green, and blue. To form

When a green organic EL film is formed,
Alq as base material for organic EL film _Three(Tris-8-key
Quinacridone is also used
Alternatively, coumarin 6 is added as a dopant. Also,
When forming a red organic EL film, the base material of the organic EL film
Alq as a charge_ThreeUsing DCJT, DCM1 or
DCM2 is added as a dopant. In addition, blue
When forming the organic EL film, B is used as the organic EL film of the light emitting layer.
Alq_Three(2-methyl-8-quinolinol and phenol
Pentacoordination complex with mixed ligands of derivatives)
Len is added as a dopant.

It is needless to say that the present invention is not limited to the above-mentioned organic EL film, and it is possible to use a known low-molecular-weight organic EL film or a known high-molecular-weight organic EL film. Polymer organic EL
When a film is used, a coating method (a spin coating method, an inkjet method, or a printing method) can be used.

As described above, the organic EL films 331, 33
2 is formed, and the second transparent electrode 333 is formed of 20 nm.
MgAg film having a thickness of 1 to 10
% Of silver (Ag) is added, and an ITO film having a thickness of 250 nm is formed as the third transparent electrode 334. In this embodiment, the cathode 341 is formed by the second transparent electrode 333 and the third transparent electrode 334.

Thus, the anode 340 and the organic EL film 331
The EL element 400 including the (or the organic EL film 332) and the cathode 341 is formed. In this embodiment, this EL element functions as a light emitting element.

Next, as shown in FIG.
An auxiliary electrode 336 made of a transparent conductive film is
m, and a conductor 337 made of an anisotropic conductive film is provided on the third transparent electrode 334. Then, the substrate 301 and the sealing body 335 are formed using a sealing material (not shown).
And stick them together.

The bonding step is performed in an argon atmosphere. As a result, the space 338 is filled with argon. Of course, the gas to be filled may be an inert gas, and a nitrogen gas or a rare gas may be used. In addition, space 33
8 is preferably provided with a substance that adsorbs oxygen or water. Further, instead of forming a space, it is also possible to fill with a resin.

By the above-described manufacturing process, the switching TFT (the p-channel type TF in this embodiment) is provided in the pixel.
T) 401 and a current control TFT (p-channel type TFT in this embodiment) 402 are formed. In this embodiment, since all the TFTs are p-channel TFTs, the manufacturing process is very simple.

The step is flattened by the second interlayer insulating film 324, and the drain wiring 321 of the current control TFT 402 and the pixel electrode 328 are connected to the contact hole 3.
Since the electrical connection is made using the conductor plug 327 embedded in the anode 25, the flatness of the anode 340 is high. Therefore, the uniformity of the film thickness of the organic EL film 332 can be improved, so that the light emission of the pixel can be made uniform.

Embodiment 2 In this embodiment, an EL light emitting device having a pixel having a structure different from that of the EL light emitting device shown in FIG. 2 will be described with reference to FIG. Note that this embodiment can be manufactured only by making some changes to the structure of FIG.
A description will be given focusing on the differences from FIG. Therefore, the description of the portions denoted by the same reference numerals as in FIG. 2 may be referred to “Embodiments of the Invention”.

In this embodiment, after a contact hole is formed in the interlayer insulating film 205, a pixel electrode 701 and a first transparent electrode 702 are formed in that state, and an insulating film 703 is formed so as to fill a recess formed by the contact hole. In this embodiment, this insulating film 703 is called a buried insulating film. Since the buried insulating film 703 can be formed simultaneously with the bank 209, the number of steps is not particularly increased.

The buried insulating film 703 is for preventing a short circuit between the cathode and the anode caused by the concave portion due to the contact hole, similarly to the conductor plug 206 of FIG. At this time, the height between the upper surface of the buried insulating film 703 and the upper surface of the second transparent electrode 702 is 100 to 300 n.
m is preferable. If the height exceeds 300 nm, the step may cause a short circuit between the cathode and the anode. If the thickness is less than 100 nm, the effect of the simultaneously formed bank 209 (the effect of suppressing the effect of electric field concentration at the edge of the pixel electrode) may be reduced.

In this embodiment, after the second transparent electrode 702 is formed, an acrylic resin is formed to a thickness of 500 nm by spin coating, and oxygen gas is turned into plasma to form the acrylic film (except outside the contact hole). Is etched until the film thickness becomes 200 nm. After reducing the film thickness in this manner, patterning is performed to form the bank 209 and the buried insulating film 703.

FIG. 8 shows the top structure of the pixel of this embodiment. 8 is a sectional view taken along the line AA ′ in FIG.
Is equivalent to FIG. 8 shows the sealing body 215 and the conductor 217.
Is not shown. In addition, since the basic pixel structure is the same as that of FIG. 5, detailed description will be omitted.

In FIG. 8, the bank 209 is a pixel electrode 7
01, formed so as to hide the step at the end of the anode 702,
The buried insulating film 703 is formed by projecting a part of the bank 209. The protruding insulating film serves as the pixel electrode 701.
Of the contact hole.

The EL light emitting device of this embodiment can be easily manufactured by combining the manufacturing method of Embodiment 1 with the method of forming the buried insulating film.

[Embodiment 3] Although only the structure of the pixel portion is shown in the EL light emitting device shown in the embodiment of the present invention and the embodiment 1, a driving circuit for driving the pixel portion is integrated on the same substrate. It may be formed. At that time, the drive circuit is set to nMO
It can be formed by an S circuit, a pMOS circuit, or a CMOS circuit. Of course, only the pixel portion may be formed of TFTs, and an external drive circuit, typically a drive circuit (such as TCP or COG) including an IC chip may be used.

In the first embodiment, the pixel portion is formed only of the p-channel type TFT to reduce the number of manufacturing steps. In this case, however, the driving circuit is formed by a pMOS circuit, and the driving circuit cannot be manufactured by the pMOS. A driving circuit including a chip can also be used.

The structure of this embodiment can be implemented by freely combining with the structure of the first or second embodiment.

[Embodiment 4] This embodiment shows an example in which an amorphous silicon film (amorphous silicon film) is used as an active layer of a switching TFT and a current control TFT formed in a pixel portion. An inverted staggered TFT is known as a TFT using an amorphous silicon film. However, in this embodiment, an inverted staggered TFT can be used.

Although a TFT using an amorphous silicon film is easy to fabricate and has the disadvantage of increasing the element size, in the EL light emitting device of the present invention, the size of the TFT is determined by the effective light emission of the pixel. Does not affect area. Therefore, by using an amorphous silicon film as an active layer, a less expensive EL
A light-emitting device can be manufactured.

The configuration of this embodiment can be implemented by freely combining with any of the configurations of the first to third embodiments. However, when combined with the third embodiment,
Since it is difficult to manufacture a driving circuit with a high operation speed using a TFT using an amorphous silicon film, it is desirable to externally provide a driving circuit including an IC chip.

[Embodiment 5] In the embodiments 1 to 4, the active matrix EL light emitting device has been described.
It is also possible to carry out for the L element.

The structure of this embodiment can be implemented by freely combining with any of the structures of the first to third embodiments. However, when combined with the third embodiment, a driving circuit including an IC chip is externally provided.

[Embodiment 6] A light emitting device formed by carrying out the present invention can be used as a display portion of various electric appliances. Note that the display in which the light-emitting device is incorporated in the housing includes all information displays such as a display for a personal computer, a display for receiving a TV broadcast, and a display for displaying an advertisement.

[0098] Other electric appliances of the present invention include a video camera, a digital camera, a goggle type display (head mounted display), a navigation system, a music reproducing device (car audio, audio component, etc.), a notebook personal computer, Game devices, portable information terminals (mobile computers, mobile phones, portable game machines, electronic books, etc.), image reproducing devices (devices having a display unit for reproducing images recorded on a recording medium and displaying the images) Is mentioned. Specific examples thereof are shown in FIGS.

FIG. 10A shows an EL display.
A housing 2001, a support base 2002, and a display unit 2003 are included. The light emitting device of the present invention can be used for the display portion 2003. Since the EL display is a self-luminous type, it does not require a backlight and can be a display portion thinner than a liquid crystal display.

FIG. 10B shows a video camera, which includes a main body 2101, a display section 2102, an audio input section 2103, operation switches 2104, a battery 2105, and an image receiving section 210.
6 inclusive. The light emitting device of the present invention can be used for the display portion 2102.

FIG. 10C shows a digital camera, which includes a main body 2201, a display section 2202, an eyepiece section 2203, and operation switches 2204. The light emitting device of the present invention has a display unit 2
202.

FIG. 10D shows an image reproducing apparatus (specifically, a DVD reproducing apparatus) provided with a recording medium.
1, a recording medium (CD, LD, DVD, etc.) 2302,
An operation switch 2303, a display unit (a) 2304, and a display unit (b) 2305 are included. The display unit (a) mainly displays image information, and the display unit (b) mainly displays character information. The light emitting device of the present invention employs these display units (a) and (b).
Can be used. Note that the image reproducing device provided with the recording medium may include a CD reproducing device, a game machine, and the like.

FIG. 10E shows a portable (mobile) computer, which includes a main body 2401, a display portion 2402, an image receiving portion 2403, operation switches 2404, and a memory slot 24.
05 inclusive. The electro-optical device of the invention can be used for the display portion 2402. This portable computer can record information on a recording medium in which a flash memory or a nonvolatile memory is integrated, and can reproduce the information.

FIG. 10F shows a personal computer, which includes a main body 2501, a housing 2502, a display portion 2503,
A keyboard 2504 is included. The light-emitting device of the present invention can be used for the display portion 2503.

If the emission luminance of the EL material becomes higher in the future, it becomes possible to enlarge and project the light containing the output image information with a lens or the like and use it for a front-type or rear-type projector.

Further, the above-mentioned electronic device can be connected to the Internet or C
Information distributed through an electronic communication line such as an ATV (cable television) is frequently displayed, and in particular, opportunities to display moving image information are increasing. Since the response speed of the EL material is very high, it is suitable for displaying such a moving image.

In the light emitting device, since the light emitting portion consumes power, it is desirable to display information so that the light emitting portion is reduced as much as possible. Therefore, when the light emitting device is used for a portable information terminal, particularly a display portion mainly for text information such as a mobile phone or car audio, the non-light emitting portion is driven to form the text information with the light emitting portion on the background. It is desirable.

Here, FIG. 11A shows a mobile phone, which includes a main body 2601, a voice output unit 2602, and a voice input unit 260.
3, including a display unit 2604, operation switches 2605, and an antenna 2606. The light emitting device of the present invention can be used for the display portion 2604. Note that the display portion 2604 can display power of the mobile phone by displaying white characters on a black background.

FIG. 11B shows a car audio, which includes a main body 2701, a display portion 2702, and an operation switch 27.
03, 2704. The light-emitting device of the present invention has a display unit 27.
02 can be used. In this embodiment, the in-vehicle car audio is shown, but it may be used for a stationary car audio. Note that the display portion 2704 can suppress power consumption by displaying white characters on a black background.

Furthermore, it is effective to provide a function of modulating the light emission luminance in accordance with the brightness of the use environment by incorporating a light sensor and providing a means for detecting the brightness of the use environment. The user can recognize the image or the character information without any problem if the brightness of the contrast ratio of 100 to 150 can be secured as compared with the brightness of the use environment. In other words, if the usage environment is bright, increase the brightness of the image to make it easier to see,
When the usage environment is dark, it is possible to suppress the power consumption by suppressing the brightness of the image.

As described above, the applicable range of the present invention is extremely wide, and the present invention can be used for electric appliances in various fields. Further, the electric appliance of the present embodiment may use the light emitting device having any configuration shown in the first to fifth embodiments.

[0112]

According to the present invention, an electrode made of a transparent conductive film provided on the sealing body side is an anisotropic conductive film with respect to an electrode made of a transparent conductive film formed after forming an organic EL film. It is characterized in that it is electrically connected by using. Thereby, the resistance value of the transparent conductive film formed after forming the organic EL film can be substantially reduced, and a uniform voltage can be applied.

In the present invention, the cathode is transparent or translucent, and a reflective electrode is provided under the EL element to combine with a light emitting device having a structure in which light is extracted to the cathode side. And a light-emitting device having a significantly improved image quality and good image quality can be obtained. Also,
An electric appliance having good image quality using the light emitting device of the present invention as a display portion can be obtained.

[Brief description of the drawings]

FIG. 1 illustrates a cross-sectional structure of a light-emitting device.

FIG. 2 illustrates a cross-sectional structure of a light-emitting device.

FIG. 3 illustrates a manufacturing process of a light-emitting device.

FIG. 4 illustrates a manufacturing process of a light-emitting device.

FIG. 5 illustrates a top structure and a circuit configuration of a pixel of a light-emitting device.

FIG. 6 illustrates a cross-sectional structure of a storage capacitor.

FIG. 7 illustrates a cross-sectional structure of a light-emitting device.

FIG. 8 illustrates a top structure of a light-emitting device.

FIG. 9 illustrates a cross-sectional structure of a conventional light emitting device.

FIG. 10 illustrates a specific example of an electric appliance.

FIG. 11 illustrates a specific example of an electric appliance.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H05B 33/14 H05B 33/14 A 33/24 33/24 33/28 33/28 F-term (Reference) 3K007 AB02 AB05 AB18 BA06 BB01 BB07 CA01 CA02 CA05 CB01 CB03 CC00 DA01 DB03 EA01 EB00 FA02 5C094 AA04 AA07 AA08 AA43 AA47 AA48 AA53 AA55 BA03 BA27 CA19 CA24 CA25 DA09 DA12 DA13 DB01 DB02 DB04 DB05 EA02 EA02 EB02 EA01 EB02 JA08

Claims (12)

[Claims] 1. A light emitting device comprising: an electrode including a reflection surface; an EL element including an organic EL layer and a transparent electrode; and an auxiliary electrode connected to the transparent electrode via a conductor. 2. The light emitting device according to claim 1, wherein the electrode including the reflection surface is made of a metal film, and the transparent electrode is made of a transparent conductive film. 3. The electrode according to claim 1, wherein the electrode including the reflection surface is formed by laminating a metal film and a transparent conductive film, and the transparent electrode is formed by laminating a translucent metal film and a transparent conductive film. Light emitting device. 4. The light emitting device according to claim 3, wherein an organic EL layer is provided in contact with the transparent conductive film and the translucent metal film included in the electrode including the reflection surface. 5. The light emitting device according to claim 3, wherein said semitransparent metal film has a thickness of 5 to 70 nm. 6. A light emitting device according to claim 1, wherein said auxiliary electrode is made of a transparent conductive film. 7. An electric appliance using the light emitting device according to claim 1. Description: 8. An electrode including a reflective surface is formed on an insulator,
Forming an organic EL layer on the electrode including the reflection surface, forming a transparent electrode on the organic EL layer, and forming a conductor on the transparent electrode; Forming an electrode, and bonding the insulator and the sealing member so that the conductor and the auxiliary electrode are connected to each other. 9. The method for manufacturing a light emitting device according to claim 8, wherein the electrode including the reflection surface is formed of a metal film, and the transparent electrode is formed of a transparent conductive film. 10. The method according to claim 8, wherein the electrode including the reflection surface is formed by laminating a metal film and a transparent conductive film, and the transparent electrode is formed by laminating a translucent metal film and a transparent conductive film. A method for manufacturing a light-emitting device, comprising: 11. A method for manufacturing a light emitting device according to claim 10, wherein said translucent metal film has a thickness of 5 to 70 nm. 12. The method for manufacturing a light emitting device according to claim 8, wherein the auxiliary electrode is formed of a transparent conductive film.