JP2002184569A - Luminescent device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sealing technology for an EL panel of a luminescent device. SOLUTION: An EL element 106 inside a sealed space is provide on it with an absorbent film 107 made of metal having behavior of absorbing water, oxygen or the like (absorbency). With this, it is made easy to give a space 109 a function of absorbing water or oxygen inside as well as to form an absorbent film after another continuously after an EL element 106 is formed, whereby, a sealing structure can be formed without letting in oxygen or moisture inside the space, and thus, the EL element is prevented from degradation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a device (hereinafter, referred to as an EL device) formed by forming an EL (electroluminescence) element on a substrate.
A light-emitting device). In particular, the present invention relates to a technique for sealing an EL panel in which a light emitting device has an EL element formed over a substrate. In this specification, the FPC is used for the EL panel.
Are connected, and a module on which an IC (integrated circuit) is directly mounted via an FPC is called a light emitting device.

[0003]

2. Description of the Related Art In recent years, light-emitting devices having an EL element as a light-emitting element have been actively researched. In particular, a light-emitting device using an organic material as an EL material has attracted attention. This light emitting device is an organic EL display (OELD: Organi)
c EL Display) or Organic Light Emitting Diode (OLED).

[0004] Unlike a liquid crystal display device, a light emitting device is of a self-luminous type, and thus has a feature that there is no problem of a viewing angle. That is, as a display used outdoors, it is more suitable than a liquid crystal display, and its use in various forms has been proposed.

An EL element has a structure in which an EL layer is sandwiched between a pair of electrodes. The EL layer usually has a laminated structure. A typical example is a laminated structure of “hole transport layer / light emitting layer / electron transport layer” proposed by Tang et al. Of Kodak Eastman Company. This structure has a very high luminous efficiency, and most light emitting devices currently under research and development are adopting this structure.

In addition, a hole injection layer / hole transport layer / light-emitting layer / electron transport layer, or a hole injection layer / hole transport layer / light-emitting layer / electron transport layer / electron injection layer may be formed on the anode. A structure in which layers are sequentially stacked is also good. The light emitting layer may be doped with a fluorescent dye or the like. Further, these layers may be formed entirely of a film made of a low molecular material, or may be formed entirely of a film made of a high molecular material.

In this specification, all layers provided between a cathode and an anode are collectively called an EL layer. Therefore, the above-described hole injection layer, hole transport layer, light emitting layer, electron transport layer, and electron injection layer are all included in the EL layer.

In this specification, a light-emitting element formed by a cathode, an EL layer, and an anode is called an EL element, and includes an EL element between two types of stripe-shaped electrodes provided to be orthogonal to each other. There are two types: a method of forming an EL layer (simple matrix method) and a method of forming an EL layer between a pixel electrode connected to a TFT and arranged in a matrix and a counter electrode (active matrix method).

Among the EL devices, those using a fluorescent organic compound for the EL layer are called organic EL devices.
The biggest problem in practical use of an organic EL device is that the lifetime of the device is insufficient. In addition, the deterioration of the element appears in a form in which light is emitted for a long time and a non-light-emitting area (dark spot) is widened. It is said that the largest cause is caused by peeling of the cathode.

[0010] Occurrence of dark spots due to oxidation or peeling of the cathode is often caused by oxygen or moisture in the atmosphere. For example, when an electrode made of a stable metal such as an MgAg alloy is used, the element can be operated in the air, but the life of the element is shortened. Therefore, in order to obtain good device characteristics, it is ideal that the device is manufactured consistently in a glove box under a vacuum or an inert gas atmosphere.

That is, in order to manufacture a device having a practical life, a sealing technique is important. Generally, the element is covered with a glass substrate under an atmosphere of dry nitrogen or inert gas,
A method of sealing the periphery with a resin is adopted.

However, dark spot growth is observed even on the sealed substrate. It is considered that this is because a reaction between the electrode and the residual impurities is promoted by a high electric field when the element is driven. That is, it is difficult to completely remove substances such as oxygen and moisture because there are surface adsorbed substances and substances released from the sealing resin even if the purity of the enclosed gas is increased. On the other hand, the following measures have been taken.

FIG. 16 shows a cross-sectional structure in sealing a general EL panel. In FIG. 16, reference numeral 1601 denotes a substrate;
Reference numeral 1602 denotes an anode, 1603 denotes an EL layer, and 1604 denotes a cathode. The anode 1602 and the cathode 1604 are each electrically connected to an external power supply. And the anode 160
2. Substrate 1 including EL layer 1603 and cathode 1604
The EL element on 601 is sealed by a sealing substrate 1607 via a sealant 1608.

Here, in order to prevent deterioration of the EL element due to oxygen and moisture existing in the space 1609, a moisture absorbing agent (also referred to as a water catching agent) 1606 made of a hygroscopic substance is added. This is described in detail in the following literature. (Literature: Shin Kawami, Takemi Naito, Hiroshi Ohata, Hitoshi Nakata: Effect of water-trapping agent on encapsulation of organic EL devices, Proc. Of the 45th JSAP Lecture on Applied Physics, 1
223 (1998))

The hygroscopic agent includes a physically adsorbing agent represented by silica gel and synthetic zeolite, and a chemisorbing agent represented by phosphorus pentoxide and calcium chloride. As the substance (1), a chemisorbing substance such as barium oxide (BaO) is often used because the absorbed water is taken in as crystal water and is not released again.

As a method of providing a hygroscopic agent, a space (a dent or the like) for providing a hygroscopic agent is provided in a sealing substrate, and after the hygroscopic agent is provided therein, a film of a synthetic resin or the like is made to have adhesiveness. To prevent the moisture absorbent from dispersing in the space 1609 by, for example, attaching the moisture absorbent in a space 1609 so as not to disperse the moisture absorbent, or attaching the moisture absorbent in a bag made of a breathable material to the sealing substrate. The method has been adopted.
However, a method of directly dispersing the moisture absorbent in the space 1609 and providing the moisture absorbent is provided.

[0017]

As shown in FIG. 16, the space 1609 is provided with a hygroscopic agent 1606 such as barium oxide.

Since the moisture absorbent such as barium oxide is usually a powdery solid, it is provided by being dispersed in the space 1609 as it is, or a material wrapped with a film made of a polymer material is sealed. A method has been adopted in which it is provided by attaching it to a substrate or the like.

Further, since the moisture absorbent is generally sealed by hand, it is difficult to work in an inert gas atmosphere, and when a packaged moisture absorbent is provided, the packaging is troublesome. Problem.

On the other hand, in some cases, the moisture absorbent is sealed in the air due to the difficulty of working in an inert gas atmosphere. However, in this case, the problem that oxygen and moisture in the atmosphere are naturally contained in the space 1609 cannot be avoided.

In view of the above, the present invention has a structure in which water and oxygen do not enter when sealing an EL element, and furthermore, a method of easily and efficiently adding a moisture absorbent or the like that absorbs these. To prevent the EL element from deteriorating.

[0022]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention has a property to absorb impurities such as oxygen and water added to the inside of an EL device formed on a substrate when the device is sealed. , Absorptivity) and the method of addition. Thus, an absorptive film (hereinafter, referred to as an absorption film) can be easily formed on the EL element, and furthermore, deterioration of the EL element due to oxygen or moisture can be prevented.

In the present invention, first, an anode, E
An EL element including an L layer and a cathode is formed, and an absorption film is formed on the EL element. Note that the absorbing film in the present invention is a metal having a low work function that is easily oxidized by oxygen, and a material such that the oxide reacts with water to form a hydrate and does not cause re-emission of moisture. Refers to a film composed of In addition, as these metal materials, alkaline earth metals such as beryllium, magnesium, calcium, strontium, barium, and radium can be used. In this specification, a film made of such a material is called an absorption film.

As a method of forming these absorbing films,
Although a vapor deposition method and a sputtering method are mentioned, a method capable of continuously forming a film after forming an EL element is preferable. In addition, when using the vapor deposition method, a method by resistance heating (RE method: Re method)
sistivity evaporation method) and electron beam method (E
B method: Electron beam method) can be used.

Further, these absorbing films may be provided directly on the EL element. However, in order to prevent moisture adsorbed on the absorbing film from directly contacting the electrodes of the EL element, insulating films such as silicon nitride and silicon oxide are used. It may be formed after a barrier film made of a film is formed on the EL element.

The absorption film is formed so as to cover the EL element, but is selectively formed using a metal mask or the like so as to surround the EL element and not to overlap with a sealing agent provided later. It is necessary to form a film.

After the formation of the absorbing film, the sealing substrate is provided at a position where the EL element is sandwiched between the substrate and the substrate, and a sealing agent is provided between the substrate and the sealing substrate to form a sealing structure. That is, oxygen, moisture, and the like existing inside the sealing structure formed here are captured by the absorption film formed earlier.

The sealant provided here is preferably a thermosetting resin or an ultraviolet curable resin. Note that the sealant is provided so as to surround the absorption film formed on the EL element.

In the present invention, after the above-described sealing structure is formed, a metal film or the like is further provided so as to cover the sealing substrate and the sealant, and oxygen and moisture are contained in the sealed interior. It may have a structure that makes it more difficult to penetrate.

However, in this case, an insulating film made of silicon nitride or silicon oxide is previously formed on a wiring (connection wiring) formed outside the sealing structure and electrically connected to the electrode of the EL element. You need to keep it. In addition, a connection portion formed for connecting the EL element to an external drive circuit needs to be blocked by a metal mask or the like so that a metal film is not formed.

[0031]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In an embodiment of the present invention,
A method for sealing an EL element formed over a substrate will be described.

FIG. 1A shows a top view of an EL panel used in the present invention, and FIG. 1B shows a sectional structure thereof.

In FIGS. 1A and 1B, reference numeral 101 denotes a substrate, and 102 denotes a sealing substrate.
02, an EL element 106 is provided. Note that the EL element 106 has a structure in which the EL layer 105 is provided between the anode 103 and the cathode 104.

The anode 103 for forming the EL element is
Formed by the sputtering method, the material is ITO, which is an alloy of tin oxide and indium oxide, a compound obtained by mixing 2 to 20% of zinc oxide (ZnO) with indium oxide, and a compound consisting of zinc oxide and gallium oxide. Can be used. Further, the cathode 104 is made of M
g: It can be formed of a metal having a small work function such as Ag or Yb. The end of the anode 103 is covered with an insulator 110 made of an insulating material.

For the EL layer 105, a film forming technique such as an evaporation method, a coating method, or a printing method can be used. Further, as the structure of the EL layer 105, a hole-injection layer, a hole-transport layer, a light-emitting layer, an electron-transport layer, an electron-injection layer, a hole-blocking layer, a buffer layer, and any combination thereof,
It may have a single-layer structure.

The EL layer 105 includes a known organic EL.
Although a material can be used, a high-molecular (polymer) material may be used, or a low-molecular (monomer) material may be used. Further, a film made of a low molecular material and a film made of a high molecular material may be stacked.

It should be noted that the present invention is applicable not only to an active matrix type EL panel but also to a passive matrix type E panel.
The present invention can be applied to the L panel.

The absorption film 107 is formed to completely cover the EL element 106 formed on the substrate 101.
The absorption film 107 formed here is continuously formed in an atmosphere of an inert gas such as nitrogen or a rare gas after the EL element 106 is formed.

Further, the sealing structure of the sealing substrate 102 is formed by a sealant 108 made of a material such as a thermosetting resin or an ultraviolet curing resin. Here, a region surrounded by the substrate 101 and the sealing substrate 102 is The EL element 106 is located inside the space 109 containing an inert gas. Note that the sealant is provided at a position that does not overlap with the absorbing film.

In FIG. 1B, the arrow indicates the EL element 1
6 shows the direction in which the light emitted from 06 is emitted.
That is, as the structure of the EL element 106, the EL layer 105
As viewed from above, an anode 103 is formed on the substrate 101 side, and a cathode 104 is formed on the sealing substrate 102 side.

Although the light emission direction can be changed to the direction opposite to the arrow by exchanging the element structure of the EL element between the cathode and the anode, the absorption film 107 used in the present invention is used.
Since the transmittance decreases as moisture is adsorbed, it is preferable to use an element structure as shown in FIG.

FIGS. 1A and 1B illustrate a case where one EL panel is formed from one substrate. The present invention can be applied to a case where a plurality of panels are formed from one substrate.

After the EL element 106 is formed, the absorption film 107 is formed continuously. The absorbing film 107 formed here is formed of a metal having a low work function. In addition,
The metal having a low work function in the present specification is 2.0 to
A metal exhibiting a work function in the range of 4.0 eV.

The absorption film 107 used in the present invention is preferably formed by vapor deposition in view of the film formation temperature. However, if the treatment can be performed at a low temperature, the absorption film 107 may be formed by CVD or sputtering. It is also possible.

Next, when the absorbing film 107 is formed, sealing is performed under an inert gas atmosphere. The sealing substrate 102 used for sealing is made of glass, quartz, plastic (including plastic film), Materials such as metal (typically, stainless steel) ceramics can be used.
In addition, as plastic, FRP (Fiberglass-Rei
nforced Plastics) plate, PVF (polyvinyl fluoride) film, mylar film, polyester film, and acrylic resin film.

According to the present invention, when oxygen, moisture, or the like is mixed in the space formed by the sealing with the above structure, it is possible to prevent these from directly entering the EL element 106.
Preferably, the EL element is hermetically sealed by the substrate and the absorbing film, so that the EL element can be prevented from being exposed to the atmosphere of the space 109. In addition, deterioration of the EL element 106 due to oxygen or moisture can be suppressed.

[0047]

Embodiments of the present invention will be described below.

[Embodiment 1] FIG. 2 is a schematic view showing an element structure of an EL element used in carrying out the present invention. In FIG. 2, reference numeral 201 denotes a substrate, which can be formed using a light-transmitting material such as glass or quartz. Also, 202
Is an anode and is formed of ITO which is an alloy of tin oxide and indium oxide.
A compound obtained by mixing zinc oxide (ZnO), or a compound composed of zinc oxide and gallium oxide may be used. An end of the anode 202 is connected to an insulator 214 made of an insulating material.
Covered by

Next, the hole injection layer 203 and the hole transport layer 20
4. An EL layer 207 having a laminated structure including the light emitting layer 205 and the buffer layer 206 is formed. Specifically, as the hole injection layer 203, copper phthalocyanine (C
u-Pc) and PEDOT which is a polythiophene derivative
Can be formed.

When a low molecular material such as copper phthalocyanine is used, a film is formed by a vapor deposition method,
In the case of using a polymer material such as EDOT, a spin coating method or an ink jet method is preferably used. Further, as the hole transport layer 204, MTDATA or α-N
PD can be used.

Next, a known organic EL material can be used for the light emitting layer 205, and a high molecular EL material or a low molecular EL material can be used. In addition,
In this embodiment, a case is described in which a light-emitting layer including three colors of a red light-emitting layer that emits red light, a green light-emitting layer that emits green light, and a blue light-emitting layer that emits blue light is formed.

The red light emitting layer can be formed using Alq ₃ doped with DCM. In addition, an Eu complex (Eu (DCM) ₃ (Phen), an aluminum quinolylato complex (Alq ₃ ) using DCM-1 as a dopant, or the like can be used. (pyq) _{3. In} addition, aluminum quinolylato complex (Alq ₃ ) and benzoquinolinolato beryllium complex (BeBq) can be used, and aluminum quinolylato complex (Alq) can be used. ₃ ) It is also possible to use a material using a material such as coumarin 6 or quinacridone as a dopant, and to provide DPVBi which is a distyryl derivative, a zinc complex having an azomethine compound as a ligand, and perylene in DPVBi. A doped one can be used.

As the buffer layer 206, lithium fluoride (LiF), aluminum oxide (Al ₂ O ₃ ),
A material such as lithium acetylacetonate (Liacac) can be used.

Thus, the stacked structure of the EL layer 207 is completed. Note that when the material for forming the EL layer is a low molecular material, it may be formed by an evaporation method. When a high molecular material is used, a coating method such as a spin coating method or an inkjet method may be used. What is necessary is just to form using the method and the printing method.

Next, a cathode 208 is formed on the EL layer 207. Considering that electrons are injected from the cathode, a metal material having a low work function is required. However, metals having a low work function are unstable in the atmosphere, and oxidization and peeling pose problems. Therefore, magnesium (Mg) and silver (Ag)
It is effective to use an alloy (MgAg) formed by co-evaporation at a ratio of 9: 1. Further, as a cathode material, an alloy of aluminum and lithium, calcium and magnesium may be used. Further, ytterbium (Yb) can be used.

In this embodiment, the protection electrode 209 made of silver (Ag) is provided for the purpose of reducing the resistance at the cathode and suppressing the oxidation of the cathode. Note that the protection electrode is not necessarily provided, and may be provided as needed.

Next, a barrier film 210 is formed. Here, it is provided to prevent oxygen and moisture absorbed by the absorption film from directly contacting the cathode. Note that the barrier film is not necessarily provided, and may be provided as needed.
Note that as a material for forming the barrier film, an insulating material, specifically, a material such as copper phthalocyanine, silicon nitride, or silicon oxide may be used.

Next, an absorption film 211 is formed on the barrier film 210. As the absorption film 211, a metal having a small work function is used. This is because metals having a small work function are easily oxidized. Further, as the metal used here, an oxide generated by oxidation takes in moisture and becomes a hydrate. Specifically, barium (Ba) can be used. Barium is known to react with oxygen and water as follows.

2Ba + O ₂ → 2BaO

[0060] _{BaO + 9H 2 O → Ba (} OH) 2 · 8H 2 O

That is, as shown in this equation, barium has a function of reacting with oxygen, moisture and the like existing in the space and taking it in. That is, this chemical property is used as an absorption film.

The formation of the EL layer 207, the cathode 208, the protective electrode 209, the barrier film 210 and the absorption film 211
It is preferable to perform the treatment so that oxygen or moisture is not contained at the interface. Therefore, it is necessary to continuously form these films under a vacuum condition or to form the EL layer 207 in an atmosphere of an inert gas such as nitrogen or a rare gas, and then avoid contact with oxygen or moisture.

In the present embodiment, the above-described film formation can be performed by using a film forming apparatus of a multi-chamber system (cluster tool system).

After forming as described above, the sealant 21
2, the sealing substrate 213 is attached to the substrate 201. In this embodiment, an ultraviolet curable resin is used as the sealant 212. In this specification, the substrate 201,
A region surrounded by the sealing substrate 213 and the sealant 212 is called a space 215.

As the sealing substrate, a material such as glass, quartz, plastic (including plastic film), and metal (typically, stainless steel) ceramics can be used. In addition, as plastic, FRP (Fi
(Berglass-Reinforced Plastics) plate, PVF (polyvinyl fluoride) film, mylar film, polyester film, and acrylic resin film can be used.

In this example, the state of deterioration of the EL element having the above-described sealing structure from the time of manufacturing the panel was evaluated by the luminance obtained with respect to the voltage applied to the EL element. Although not shown in FIG. 2, the anode and the cathode of the EL element are each electrically connected to an external power supply.

The element configuration of the EL element used for the evaluation is as follows. First, after forming an anode with ITO on a glass substrate, an EL layer is formed. EL
The layer has the following laminated structure.

First, copper phthalocyanine was formed to a thickness of 20 nm as a hole injection layer, and then (4,
4 ', 4''-tris (3-methylphenylphenylamino) triphenylami
ne) (hereinafter referred to as “MTDATA”) at 20 nm,
4,4′-bis (N- (1-naphthyl) -N-phenyl-amino) -biphenyl (hereinafter referred to as “α-NPD”) is formed to a thickness of 10 nm, and then tris ( 8-quinolinolato) -aluminum (hereinafter referred to as “Al
q ₃ ) is formed to a thickness of 50 nm, and lithium acetylacetonate (hereinafter referred to as “Li
acac ") to a thickness of 2 nm. Thus, an EL layer is formed.

Next, as a cathode, Mg: Ag
Then, Ag was formed thereon to a thickness of 150 nm as a protective electrode. The thus-formed EL element, in which a sealing structure was formed using a glass substrate and an ultraviolet curable resin under a nitrogen atmosphere, was referred to as “No Ba”. Further, copper phthalocyanine was used as a barrier film on the protective electrode.
0 nm, barium was formed thereon to a thickness of 1500 nm, and a sealing structure was formed using a glass substrate and an ultraviolet curable resin in a nitrogen atmosphere.
And

FIG. 3 shows the results obtained here. The initial characteristics of the manufactured EL element were taken as the date of manufacture, and the results measured after standing for one day under a high-temperature and high-humidity condition of a temperature of 60 ° C. and a humidity of 95% were measured for one day and two days. Days after. The driving voltage here is 7V.

From the results shown in FIG. 3, it can be seen from the results that the luminance of the EL element of "No Ba" slightly decreased after one day, and decreased by 1000 candela or more two days later, whereas the EL element of "with Ba" decreased.
The device shows almost no decrease in luminance even after 2 days.

Further, FIG. 11 shows a photograph of the EL element observed “No Ba” for the EL element.
FIG. 12 shows a photograph of the EL element having “with”. Note that FIG.
12 and FIG. 12, (A) shows the E
The state of the L element is shown, (B) shows EL after leaving it for one day under high temperature and high humidity conditions, and (C) shows EL after leaving it for two days.
The state of each element is shown.

In FIG. 11, it is confirmed that the EL element “without Ba” has already deteriorated one day later. On the other hand, the EL element with “Ba” in FIG. 12 does not show any deterioration after one day. Two days later, some signs of deterioration are seen, but the EL element with “Ba” has a lower E value.
It can be seen that the deterioration of the L element is delayed. Therefore, it was confirmed that the deterioration of the EL element can be suppressed by forming the absorption film made of barium.

[Embodiment 2] Next, in this embodiment, a case where the present invention is applied to an active matrix type light emitting device will be described. First, a pixel portion and a TFT (n-channel type TF) of a driving circuit provided around the pixel portion on the same substrate are provided.
T and p-channel TFTs) at the same time,
A method for forming up to the L element will be described in detail with reference to FIGS.

First, in this embodiment, Corning # 70
A substrate 300 made of glass such as barium borosilicate glass represented by 59 glass or # 1737 glass, or aluminoborosilicate glass is used. Note that the substrate 300 is not limited as long as it is a light-transmitting substrate, and a quartz substrate may be used. Further, a plastic substrate having heat resistance enough to withstand the processing temperature of this embodiment may be used.

Next, a base film 301 made of an insulating film such as a silicon oxide film, a silicon nitride film, or a silicon oxynitride film is formed on the substrate 300. Although a two-layer structure is used as the base film 301 in this embodiment, a single-layer film of the insulating film or a structure in which two or more layers are stacked may be used. As the first layer of the base film 301, SiH ₄ , N 2
The silicon oxynitride film 301a formed by using H ₃ and N ₂ O as a reaction gas is formed to a thickness of 10 to 200 nm (preferably 50 to 10 nm).
0 nm). In this embodiment, a 50 nm-thick silicon oxynitride film 301a (composition ratio: Si = 32%, O = 27%,
N = 24%, H = 17%). Next, as a second layer of the base film 301, a plasma CVD
A silicon oxynitride film 301b formed by using iH ₄ and N ₂ O as a reaction gas has a thickness of 50 to 200 nm (preferably 100 nm).
(About 150 nm). In this embodiment, a 100-nm-thick silicon oxynitride film 301b (composition ratio Si =
32%, O = 59%, N = 7%, H = 2%).

Next, the semiconductor layer 302 is formed on the base film 301.
To 306 are formed. The semiconductor layers 302 to 306 are formed by forming a semiconductor film having an amorphous structure by a known means (sputtering, L
After forming a film by a PCVD method or a plasma CVD method, a known crystallization treatment (a laser crystallization method, a thermal crystallization method, or a thermal crystallization method using a catalyst such as nickel).
Is performed and the crystalline semiconductor film obtained is patterned into a desired shape. The semiconductor layers 302 to 306 are formed to have a thickness of 25 to 80 nm (preferably 30 to 60 nm). Although there is no limitation on the material of the crystalline semiconductor film,
Preferably silicon (silicon) or silicon germanium _{(Si X Ge 1-X (} X = 0.0001~0.02)) may be formed such as an alloy. In this embodiment, the plasma CV
After a 55-nm amorphous silicon film was formed by method D, a solution containing nickel was held on the amorphous silicon film. After dehydrogenation (500 ° C., 1 hour) of this amorphous silicon film, thermal crystallization (550 ° C., 4 hours) is performed, and further, a laser annealing process for improving crystallization is performed. Thus, a crystalline silicon film was formed. Then, the crystalline silicon film is patterned by a photolithography method.
Semiconductor layers 302 to 306 were formed.

After the formation of the semiconductor layers 302 to 306, a slight amount of impurity element (boron or phosphorus) may be doped in order to control the threshold value of the TFT.

When a crystalline semiconductor film is formed by a laser crystallization method, a pulse oscillation type or continuous emission type excimer laser, a YAG laser, or a YVO ₄ laser can be used. In the case of using these lasers, it is preferable to use a method in which laser light emitted from a laser oscillator is linearly condensed by an optical system and irradiated on a semiconductor film. The crystallization conditions are appropriately selected by the practitioner. When an excimer laser is used, the pulse oscillation frequency is set to 300 Hz, and the laser energy density is set to 100 to 4.
(Typically 200~300mJ / cm ²⁾ 00mJ / cm2 to.
When a YAG laser is used, it is preferable that the second harmonic is used, the pulse oscillation frequency is 30 to 300 Hz, and the laser energy density is 300 to 600 mJ / cm ² (typically 350 to 500 mJ / cm ² ). And width 100
A laser beam condensed linearly at ~ 1000 μm, for example 400 μm, is irradiated over the entire surface of the substrate, and the superposition rate (overlap rate) of the linear laser light at this time is 50-9.
What is necessary is just to set it as 0%.

Next, a gate insulating film 307 covering the semiconductor layers 302 to 306 is formed. The gate insulating film 307 is formed by a plasma CVD method or a sputtering method and has a thickness of 40 to
The insulating film containing silicon is formed to have a thickness of 150 nm. In this embodiment, a silicon oxynitride film (composition ratio: Si = 32%, O = 59%, N =
7%, H = 2%). Needless to say, the gate insulating film is not limited to the silicon oxynitride film, and another insulating film containing silicon may be used as a single layer or a stacked structure.

When a silicon oxide film is used, TEOS (Tetraethyl Orthosilicate) is formed by a plasma CVD method.
And O ₂ , a reaction pressure of 40 Pa and a substrate temperature of 300 to
400 ° C., high frequency (13.56 MHz) power density 0.
It can be formed by discharging at 5 to 0.8 W / cm ² .
The silicon oxide film thus manufactured is thereafter
Good characteristics as a gate insulating film can be obtained by thermal annealing at up to 500 ° C.

Next, as shown in FIG. 4A, a first conductive film 308 having a thickness of 20 to 100 nm and a second conductive film 30 having a thickness of 100 to 400 nm are formed on the gate insulating film 307.
9 are laminated. In this embodiment, a 30 nm-thick T
a first conductive film 308 made of an aN film and a film thickness of 370 nm
A second conductive film 309 made of a W film was formed by lamination. T
The aN film was formed by a sputtering method, and was sputtered using a Ta target in an atmosphere containing nitrogen. The W film was formed by a sputtering method using a W target. Thermal CV using tungsten hexafluoride (WF6)
It can also be formed by Method D. In any case, it is necessary to lower the resistance in order to use it as a gate electrode,
It is desirable that the resistivity of the W film be 20 μΩcm or less. The resistivity of the W film can be reduced by enlarging the crystal grains. However, when the W film contains many impurity elements such as oxygen, the crystallization is inhibited and the resistance is increased. Therefore, in this embodiment, the W film is formed by a sputtering method using a high-purity W (purity of 99.9999%) target, and further taking care not to mix impurities from the gas phase during film formation. By forming, a resistivity of 9 to 20 μΩcm could be realized.

In this embodiment, the first conductive film 308
Is TaN, and the second conductive film 309 is W. However, the present invention is not particularly limited, and any of Ta, W, Ti, Mo, Al, Cu,
It may be formed of an element selected from Cr and Nd, or an alloy material or a compound material containing the element as a main component.
Alternatively, a semiconductor film typified by a polycrystalline silicon film doped with an impurity element such as phosphorus may be used. Also, Ag,
An alloy made of Pd and Cu may be used. The first conductive film is formed of a tantalum (Ta) film, the second conductive film is formed of a W film, and the first conductive film is formed of titanium nitride (T
iN) film, the second conductive film is a W film, the first conductive film is a tantalum nitride (TaN) film, and the second conductive film is an Al film. The conductive film may be formed using a tantalum nitride (TaN) film and the second conductive film may be formed using a Cu film.

Next, as shown in FIG.
A mask 310 made of a resist using a graphic method
314, and a first for forming electrodes and wiring.
Perform an etching process. In the first etching process, the first
And under the second etching condition. In this embodiment, the first
Etching conditions are ICP (Inductively Coupled).
Plasma: Inductively coupled plasma) etching method
CF for gas for etching _FourAnd Cl_TwoAnd O_TwoAnd use
The gas flow ratio is 25/25/10 (sccm),
500W RF (13.56M) on coil type electrode at 1Pa pressure
Hz) Apply power and generate plasma to perform etching.
Was. Here, ICP manufactured by Matsushita Electric Industrial Co., Ltd. was used.
Dry etching equipment (Model E645-IC
P) was used. 150W also on the substrate side (sample stage)
Turn on RF (13.56 MHz) power and substantially negative self-bias
Apply a ground voltage. By this first etching condition
Etch W film to taper end of first conductive layer
State. Etch for W under first etching condition
Speed is 200.39 nm / min, relative to TaN
The etching rate is 80.32 nm / min.
The selectivity ratio of W to N is about 2.5. In addition, this
Depending on the etching condition of 1, the taper angle of W is about 2
6 °.

Then, as shown in FIG. 4B, the masks 310 to 314 made of resist are not removed and the second etching condition is changed, and CF ₄ and Cl ₂ are used as etching gases, and Gas flow ratio 30/30 (scc
m) and 500 W of R on the coil-type electrode at a pressure of 1 Pa
F (13.56 MHz) power is applied to generate plasma and about 3
Etching was performed for about 0 seconds. A 20 W RF (13.56 MHz) power is also applied to the substrate side (sample stage) and a substantially negative self-bias voltage is applied. Under the second etching condition in which CF ₄ and Cl ₂ are mixed, the W film and the TaN film are etched to the same extent. The etching rate for W under the second etching condition is 58.97 nm / mi.
n, the etching rate for TaN is 66.43 nm /
min. Note that in order to perform etching without leaving a residue on the gate insulating film, the etching time is preferably increased by about 10 to 20%.

In the first etching process, the shape of the resist mask is made appropriate,
The ends of the first conductive layer and the second conductive layer are tapered due to the effect of the bias voltage applied to the substrate side. The angle of the tapered portion may be 15 to 45 degrees. Thus, the first shape conductive layers 315 to 319 (the first conductive layers 315 a to 319 a and the second conductive layer 315 b) including the first conductive layer and the second conductive layer are formed by the first etching process.
To 319b). Reference numeral 320 denotes a gate insulating film, and a region which is not covered with the first shape conductive layers 315 to 319 is etched by about 20 to 50 nm to form a thinned region.

Then, the resist mask is removed.
The first doping process without adding an n-type semiconductor layer.
A given impurity element is added (FIG. 4B). Dopin
Can be done by ion doping or ion implantation
Good. The condition of the ion doping method is that the dose amount is 1 × 10¹³
~ 5 × 10¹⁵atoms / cm^TwoAnd the acceleration voltage is 60 to 100
Performed as keV. In this embodiment, the dose is 1.5 × 1
0¹⁵atoms / cm^TwoAnd the acceleration voltage is set to 80 keV.
Was. Element belonging to Group 15 as an impurity element imparting n-type
Using arsenic, typically phosphorus (P) or arsenic (As)
However, phosphorus (P) was used here. In this case, the conductive layer 3
15 to 319 are masses for the impurity element imparting n-type.
And the high-concentration impurity regions 321 to 32 are self-aligned.
5 are formed. The high-concentration impurity regions 321 to 325
1 × 10²⁰~ 1 × 10^{twenty one}atoms / cm ^ThreeN type in the concentration range of
An impurity element to be added is added.

Next, as shown in FIG. 4C, a second etching process is performed without removing the resist mask. Here, CF ₄ , Cl ₂ and O ₂ are used as etching gases.
And the respective gas flow rate ratios are 20/20/20
(Sccm) and a pressure of 1 Pa applies 50
An RF (13.56 MHz) power of 0 W was supplied to generate plasma to perform etching. A 20 W RF (13.56 MHz) power is also applied to the substrate side (sample stage) and a substantially negative self-bias voltage is applied. The etching rate for W in the second etching process is 124.62 nm / mi.
n, the etching rate for TaN is 20.67 nm /
min and the selectivity ratio of W to TaN is 6.05. Therefore, the W film is selectively etched. The taper angle of W became 70 ° by the second etching. By the second etching process, the second conductive layer 33 is formed.
0b to 330b are formed. On the other hand, the first conductive layer 315
a to 319a are hardly etched to form first conductive layers 330a to 334a.

Next, a second doping process is performed. The doping is performed using the second conductive layers 330b to 334b as a mask for the impurity element, so that the semiconductor element below the tapered portion in the first conductive layer is doped with the impurity element. In this embodiment, P is used as the impurity element.
Plasma doping was performed using (phosphorus) at a dose of 1.5 × 10 ¹⁴ , a current density of 0.5 μA, and an acceleration voltage of 90 keV. Thus, the low-concentration impurity regions 340 to 344 overlapping with the first conductive layer are formed in a self-aligned manner. The concentration of phosphorus (P) added to low-concentration impurity regions 340 to 344 is 1 × 10 ^{17 to} 5 × 10 ¹⁸ atoms / cm ³ , and depends on the thickness of the tapered portion in the first conductive layer. It has a gentle concentration gradient. Although the impurity concentration in the semiconductor layer overlapping the tapered portion of the first conductive layer slightly decreases from the end of the tapered portion in the first conductive layer toward the inside, the impurity concentration is approximately the same. . Further, an impurity element is also added to the high-concentration impurity regions 321 to 325, and the high-concentration impurity regions 345 to 325 are also added.
49 are formed.

Next, as shown in FIG. 5B, the mask made of resist is removed, and then a third etching process is performed by using photolithography. This third etching treatment is performed in order to partially etch the tapered portion of the first conductive layer so that the tapered portion overlaps with the second conductive layer. However, in a region where the third etching is not performed, as shown in FIG.
A mask consisting of 1) is formed.

Etching in Third Etching Process
The conditions are Cl as an etching gas. _TwoAnd SF₆Using
Each gas flow ratio is 10/50 (sccm)
ICP etching method as well as first and second etching
This is performed using The TaN in the third etching process
Is 111.2 nm / min,
The etching rate for the gate insulating film is 12.8 nm / m
in.

In this embodiment, etching was performed by applying a 500 W RF (13.56 MHz) power to the coil-type electrode at a pressure of 1.3 Pa to generate plasma. A 10 W RF (13.56 MHz) power is also applied to the substrate side (sample stage), and a substantially negative self-bias voltage is applied. Thus, first conductive layers 352a to 354a are formed.

By the third etching, impurity regions (LDs) which do not overlap with first conductive layers 352a to 354a are formed.
D regions) 355 to 357 are formed. Note that impurity regions (GOLD regions) 340 and 342 remain overlapping first conductive layers 330a and 332a.

Further, an electrode formed by the first conductive layer 330a and the second conductive layer 330b finally becomes a gate electrode of an n-channel TFT of the driver circuit, and is formed by the first conductive layer 352a and the first conductive layer 352a. The electrode formed with the second conductive layer 352b finally becomes the gate electrode of the p-channel TFT of the driver circuit.

Similarly, the electrode formed by the first conductive layer 353a and the second conductive layer 353b finally becomes the gate electrode of the n-channel TFT in the pixel portion, and the first conductive layer 354a and the second The electrode formed by the second conductive layer 354b finally becomes the gate electrode of the p-channel TFT in the pixel portion. Further, the first conductive layer 332a and the second conductive layer 3
The electrode formed by 32b finally becomes one electrode of a capacitor (holding capacity) of the pixel portion.

As described above, in this embodiment, the impurity regions (LDDs) which do not overlap with the first conductive layers 352a to 354a are formed.
Regions) 355 to 357 and impurity regions (GOLD regions) 340 and 342 overlapping with the first conductive layers 330a and 332a can be formed at the same time, and can be separately formed according to TFT characteristics.

Next, masks 350 and 35 made of resist
1 is removed, and the gate insulating film 320 is etched.
I do. Here, the etching process is performed by adding C to the etching gas.
HF _ThreeUsing reactive ion etching (RIE)
This is performed using In this embodiment, the chamber pressure is 6.7P
a, RF power 800W, CHF_ThreeGas flow rate 35sccm
Performed the fourth etching process. This allows high concentrations
A part of the impurity regions 345 to 349 is exposed and the insulating film 36 is formed.
0 to 364 are formed.

Next, a mask 3 made of a new resist
65, 366 are formed and a third doping process is performed.
By this third doping process, a p-channel TFT
Is formed (FIG. 5C). First conductive layer 35
Using 2a, 332a and 354a as a mask for the impurity element, an impurity element imparting p-type is added to form an impurity region in a self-aligned manner.

In this embodiment, the impurity regions 370 to 375
Is formed by an ion doping method using diborane (B ₂ H ₆ ). Phosphorus is added at different concentrations to the impurity regions 370 to 375 by the first doping process and the second doping process, and the concentration of the impurity element imparting p-type is 2 × in each of the regions. 10 ²⁰ ~
By performing the doping treatment at 2 × 10 ²¹ atoms / cm ³ , there is no problem because it functions as a source region and a drain region of a p-channel TFT.

Through the above steps, impurity regions are formed in the respective semiconductor layers. In this embodiment, the method of doping an impurity (boron) after etching the gate insulating film is described; however, the impurity may be doped without etching the gate insulating film, or the gate insulating film may be doped. May be doped before etching.

Next, a mask 365 made of resist is used.
After removing 366, a first interlayer insulating film 376 is formed as shown in FIG. The first interlayer insulating film 376 is formed of an insulating film containing silicon with a thickness of 100 to 200 nm by a plasma CVD method or a sputtering method. In this embodiment, a film thickness of 15
A 0 nm silicon oxynitride film was formed. Needless to say, the first interlayer insulating film 376 is not limited to a silicon oxynitride film, and another insulating film containing silicon may be used as a single layer or a stacked structure.

Next, a step of activating the impurity element added to each semiconductor layer is performed. This activation step is performed by a thermal annealing method using a furnace annealing furnace. As a thermal annealing method, the oxygen concentration is 1 ppm or less,
Preferably in a nitrogen atmosphere of 0.1 ppm or less 400 ~
700 ° C., typically at 500-550 ° C.
In this embodiment, the activation treatment is performed by heat treatment at 550 ° C. for 4 hours. Note that, other than the thermal annealing method, a laser annealing method or a rapid thermal annealing method (RTA method) can be applied.

In this embodiment, at the same time as the above-mentioned activation treatment, nickel used as a catalyst at the time of crystallization contains impurity regions (345, 348, 370,
372, 374), and the nickel concentration in the semiconductor layer mainly serving as a channel formation region is reduced.
TF having channel forming region manufactured in this manner
T has a low off-current value and high crystallinity, so that a high field-effect mobility can be obtained and good characteristics can be achieved.

Further, an activation process may be performed before forming the first interlayer insulating film. However, when the wiring material used is weak to heat, after forming an interlayer insulating film (an insulating film containing silicon as a main component, for example, a silicon nitride film) for protecting the wiring and the like as in this embodiment, the active material is activated. It is preferable to carry out a chemical treatment.

Alternatively, a doping process may be performed after the activation process to form a first interlayer insulating film.

Further, a heat treatment is performed at 300 to 550 ° C. for 1 to 12 hours in an atmosphere containing 3 to 100% of hydrogen to perform a step of hydrogenating the semiconductor layer. In this embodiment, heat treatment was performed at 410 ° C. for one hour in a nitrogen atmosphere containing about 3% of hydrogen. In this step, dangling bonds in the semiconductor layer are terminated by hydrogen contained in the interlayer insulating film. As another means of hydrogenation, plasma hydrogenation (using hydrogen excited by plasma) may be performed.

In the case where a laser annealing method is used as the activation treatment, it is desirable to irradiate a laser beam such as an excimer laser or a YAG laser after performing the above hydrogenation.

Next, as shown in FIG. 6B, a second interlayer insulating film 380 made of an organic insulating material is formed on the first interlayer insulating film 376. In this embodiment, the film thickness is 1.6 μm.
Was formed. Next, each impurity region 3
Patterning for forming a contact hole reaching 45, 348, 370, 372, 374 is performed.

As second interlayer insulating film 380, a film made of an insulating material containing silicon or an organic resin is used. As the insulating material containing silicon, silicon oxide, silicon nitride, or silicon oxynitride can be used. As the organic resin, polyimide, polyamide, acrylic, BCB (benzocyclobutene), or the like can be used.

In this embodiment, a silicon oxynitride film formed by a plasma CVD method was formed. Note that the thickness of the silicon oxynitride film is preferably 1 to 5 μm (more preferably 2 to 4 μm). A silicon oxynitride film is effective in suppressing deterioration of an EL element because moisture contained in the film itself is small. In addition, dry etching or wet etching can be used for forming the contact hole. However, considering the problem of electrostatic breakdown at the time of etching, it is preferable to use a wet etching method.

Further, in forming the contact holes here, the first interlayer insulating film 376 and the second interlayer insulating film 3 are formed.
Considering the shape of the contact hole, it is preferable to use a material forming the second interlayer insulating film 380 having a higher etching rate than the material forming the first interlayer insulating film 376 in order to simultaneously etch 80.

Each of the impurity regions 345, 348, 3
Wirings 381 to 388 that are electrically connected to 70, 372, and 374, respectively, are formed. Then, a 50 nm thick T
Although a laminated film of an i film and a 500 nm-thick alloy film (an alloy film of Al and Ti) is formed by patterning, another conductive film may be used.

Next, a transparent conductive film is formed on the
A pixel electrode 389 is formed by forming a pattern with a thickness of 0 nm and patterning (FIG. 6B). In this embodiment, indium tin oxide (IT) is used as a pixel electrode.
O) 2-20% zinc oxide (Z
A transparent conductive film mixed with nO) is used.

The pixel electrode 389 is connected to the drain wiring 3
The current control T
An electrical connection is formed with the drain region of the FT.

Next, as shown in FIG. 7, an insulating film containing silicon (a silicon oxide film in this embodiment) is formed to a thickness of 500 [nm], and an opening is formed at a position corresponding to the pixel electrode 389. Then, a third interlayer insulating film 390 functioning as a bank is formed. When the opening is formed, a tapered side wall can be easily formed by using a wet etching method. Care must be taken because if the side wall of the opening is not sufficiently smooth, deterioration of the EL layer due to a step in the side wall becomes a significant problem.

In this embodiment, although a film made of silicon oxide is used as the third interlayer insulating film 390,
In some cases, polyimide, polyamide, acrylic,
An organic resin film such as BCB (benzocyclobutene) can also be used.

Next, as shown in FIG. 7, an EL layer 391 is formed by an evaporation method. Here, an example of the EL layer 391 formed in the present invention is described.

First, copper phthalocyanine (hereinafter, referred to as “Cu—Pc”) is formed to a thickness of 20 nm as a hole injection layer on the pixel electrode (anode) 389, and MTDATA is formed as a hole transport layer to a thickness of 20 nm. α-NPD is 10 nm
After that, Alq ₃ was formed to a thickness of 50 nm as a light emitting layer, and Liacac was formed to a thickness of 2 nm as a buffer layer. From the above, E
An L layer 391 is formed.

As a material for forming the EL layer 391, a known material can be used. In this embodiment, the hole injection layer, the hole transport layer (Hole transporting layer),
4 consisting of a light emitting layer (Emitting layer) and an electron transport layer
Although the layer structure is the EL layer 391, an electron injection layer can be further provided, or a structure in which any layer other than the light emitting layer is missing is also possible. As described above, various examples of the combination have already been reported, and any of the configurations may be used.

Next, a cathode (Mg: Ag electrode) is formed by vapor deposition.
392 and a protection electrode 394 are formed. At this time, EL
Before forming the layer 391 and the cathode 392, it is preferable to perform a heat treatment on the pixel electrode 389 to completely remove moisture. In this embodiment, a Mg: Ag electrode is used as a cathode of the EL element, but other known materials may be used.

The protection electrode 394 is provided for preventing the cathode 392 from deteriorating and reducing the film resistance of the cathode, and is typically a low-resistance metal film containing aluminum as a main component. Of course, other materials may be used. The metal film is not necessarily provided, but may be provided as needed.

Further, a barrier film 395 is formed. This is to prevent oxygen or moisture captured by the absorption film provided later from coming into direct contact with the cathode and the protective electrode. In this embodiment, Cu—Pc is used as the barrier film.
Was used.

The EL layer 391 has a thickness of 10 to 400.
[nm] (typically 60 to 150 [nm]), and the thickness of the cathode 392 is 80 to 200 [nm] (typically 100 to 150 [n].
m]).

Next, the EL element 393, the protection electrode 394,
An absorption film 396 is formed to cover the barrier film 395. As the absorbing film 396, a metal having an absorptive property and a low work function is desirable, and in this embodiment, barium is used.
Note that the thickness of the absorption film 396 may be 1 to 3 [μm] (typically 1.5 to 2 [μm]).

Since the EL element 393 is susceptible to oxygen and moisture, it is desirable to continuously process from the formation of the EL layer 391 to the formation of the absorption film 396.

Further, in this embodiment, a passivation film made of an insulating film such as a nitride film or an oxide film is formed on the absorbing film 396 in order to enhance the adhesion of the sealing agent provided between the sealing substrate and the substrate at the time of sealing. The film 397 was provided. But,
This passivation film 397 is not necessarily provided, but may be provided as needed.

Thus, the structure as shown in FIG. 7 is completed. In this specification, a substrate manufactured up to the structure shown in FIG. 7 is called an EL substrate.

In this embodiment, the EL element 39
3 has a bottom emission from the element configuration of FIG.
FT503 with n-channel TFT and current control TFT5
Although a configuration in which a p-channel TFT is used is shown in FIG. 04, this embodiment is merely a preferred embodiment and need not be limited to this. Reference numerals 400 to 403 denote channel regions, 501 denotes an n-channel TFT, 502 denotes a p-channel TFT, 505 denotes a capacitor, 506 denotes a driving circuit,
507 is a pixel portion.

The driving voltage of the TFT used in this embodiment is 1.2 to 10 V, preferably 2.5 to 10 V.
~ 5.5V.

Next, a method for completing the EL panel by sealing the EL substrate shown in FIG. 7 with a sealing substrate will be described with reference to FIG.

FIG. 8A is a top view of an EL panel in which an EL substrate is sealed, and FIG. 8B is a cross-sectional view of FIG. 8A taken along line AA ′. Reference numeral 801 indicated by a dotted line denotes a source side driver circuit, 802 denotes a pixel portion, and 803 denotes a gate side driver circuit. Reference numeral 804 denotes a sealing substrate, 805 denotes a sealing material, and an inside surrounded by the sealing material 805 is a space 807.

A wiring (not shown) for transmitting signals input to the source-side drive circuit 801 and the gate-side drive circuit 803 allows a video signal or the like from an FPC (flexible print circuit) 809 serving as an external input terminal. Receive a clock signal. Note that although a state in which the FPC is connected to the EL panel is shown here, a module in which an IC (integrated circuit) is directly mounted via the FPC is referred to as a light emitting device in this specification.

Next, a cross-sectional structure will be described with reference to FIG. A pixel portion 802 and a gate side driver circuit 803 are formed above a substrate 810. The pixel portion 802 is formed by a plurality of pixels including a current control TFT 811 and a pixel electrode 812 electrically connected to a drain thereof. You. The gate side driving circuit 803 is an n-channel type TF
It is formed using a CMOS circuit (see FIG. 7) in which T813 and p-channel TFT 814 are combined.

The pixel electrode 812 functions as an anode. After the banks 815 are formed at both ends of the pixel electrode 812, the EL layer 816 and the cathode 817 are formed on the pixel electrode 812.
Are formed, and an EL element 818 is formed.

Note that the cathode 817 functions as a wiring common to all pixels, and is electrically connected to the FPC 809 via the connection wiring 808.

Next, a barrier film 819 and an absorption film 820 are continuously formed so as to cover the EL element 818. In addition,
The barrier film 819 formed here is for preventing oxygen and moisture absorbed by the absorption film 820 from directly contacting the cathode 817. Further, this is also for preventing pressure from being directly applied to the EL element 818 by the weight generated by the absorption film 820 absorbing oxygen or moisture. Therefore, as a material for forming the barrier film 819, an insulating material is preferable, and a material such as silicon nitride or silicon oxide is suitable.

As the absorbing film 820, a metal having a small work function is used. This is because metals having a small work function are easily oxidized. Further, as the metal used here, an oxide generated by oxidation takes in moisture to form a hydrate. Specifically, barium (B
a) can be used.

After the formation of the absorption film 820, a passivation film 821 is formed. This is to prevent the sealant 805 from being directly formed on the connection wiring 808. Thereby, the adhesiveness of the sealant 805 can be improved.

[0139] A sealing substrate 804 made of glass is attached by a sealant 805. Note that an ultraviolet curable resin or a thermosetting resin is preferably used as the sealant 805. Further, if necessary, a spacer made of a resin film may be provided in order to secure an interval between the sealing substrate 804 and the EL element 818. The space 807 inside the sealant 805 is filled with an inert gas such as nitrogen or a rare gas. Further, it is desirable that the sealant 805 is a material that does not transmit moisture and oxygen as much as possible.

With the above structure, the EL element is
The EL element can be completely shut off from the outside by encapsulating the EL element.
Deterioration of the L element can be prevented. Therefore, a highly reliable light-emitting device can be obtained.

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

[Embodiment 3] In this embodiment, the case where the present invention is applied to a passive matrix type (simple matrix type) light emitting device will be described. FIG. 9 is used for the description. FIG.
In the figure, 1001 is a substrate made of glass, and 1002 is an anode made of a light-transmitting conductive film. In this embodiment, as the anode 1002, a compound of indium oxide and zinc oxide is formed by a sputtering method. Although not shown in FIG. 9, a plurality of anodes 1002 are arranged in a stripe shape in a direction parallel to the paper surface. Anode 1
A bank 1003 is formed so as to fill the space between 002 and 002.

The cathodes 10 arranged in a stripe pattern
06 is formed in a direction perpendicular to the paper surface.

Next, an EL layer 1004a made of an EL material is used.
To 1004c are formed by the vapor deposition method described in the first embodiment. 1004a is an EL layer emitting red light;
4b is an EL layer that emits green light, and 1004c is an EL layer that emits blue light. The same organic EL material as that used in the first embodiment may be used. These EL layers are connected to the bank 100
3 are formed along the groove formed, so that they are formed in a stripe shape in a direction perpendicular to the paper surface.

By implementing this embodiment, pixels of three colors of red, green and blue are formed in a stripe on the substrate. The colors of the pixels are not necessarily three colors, but may be one color or two colors. Further, the color is not limited to red, green, and blue, and other colors that can be colored, such as yellow, orange, and gray, may be used.

As a method of forming an EL layer, first, only an EL layer that emits red light is formed using a metal mask, and then the metal mask is shifted to an adjacent pixel column, and then emitted green light. An EL layer is formed. Further, after moving the metal mask to an adjacent pixel column, an EL layer emitting blue light is formed, and a stripe-shaped EL layer made of red, green, and blue is formed.

The light-emitting layers of the same color may be formed one by one or at the same time.

At this time, it is desirable that the mutual distance (D) between pixels adjacent to each other in the same color line is at least 5 times (preferably at least 10 times) the thickness (t) of the EL layer. . This is because if D <5t, a problem of crosstalk between pixels may occur. Note that if the distance (D) is too large, a high-definition image cannot be obtained, so that 5t <D <5
0t (preferably 10t <D <35t).

Alternatively, the banks may be formed in stripes in the horizontal direction with respect to the plane of the paper, and the EL layer emitting red light, the EL layer emitting green light, and the EL layer emitting blue light may be formed in the same horizontal direction. good.

Also in this case, the mutual distance (D) between pixels adjacent to each other in a line of the same color is at least 5 times (preferably at least 10 times) the film thickness (t) of the EL layer, and more preferably 5t <.
It is good to set D <50t (preferably 10t <D <35t).

Using the metal mask as described above, the EL
By forming the layer, the film formation position can be controlled.

Thereafter, although not shown in FIG. 9, a plurality of cathodes and protective electrodes are arranged in a stripe shape such that the longitudinal direction is a direction perpendicular to the plane of the drawing and is orthogonal to the anode 1002. In this embodiment, the cathode 1005
Is made of MgAg, the protection electrode 1006 is made of an aluminum alloy film, and each is formed by an evaporation method. Although not shown, the wiring of the protection electrode 1006 is led out to a portion where an FPC is attached later so that a predetermined voltage is applied.

As described above, an EL element is formed on the substrate 1001. In this embodiment, since the lower electrode is a light-transmitting anode, the EL layers 1004a to 1004c
Is emitted to the lower surface (substrate 1001). However, the structure of the EL element can be reversed, and the lower electrode can be a light-shielding cathode. In that case, the EL layer 1
The light generated in 004a to 1004c is on the upper surface (substrate 1001).
To the opposite side).

After forming the protection electrode 1006, a barrier film 1307 made of an insulating material is formed. Here, an inorganic material such as silicon nitride, silicon oxide, or carbon (specifically, a DLC film) is preferably used, which can be formed by a plasma CVD method, a sputtering method, or an evaporation method. A film is formed by an evaporation method. At this time, the thickness of the barrier film 1007 is 10 n
m to 100 nm is preferred.

Next, the absorbing film 100 made of an absorbing material is used.
8 is formed by a vapor deposition method. Note that a material having a small work function and easily oxidized, such as barium, is preferably used for the absorption film used here.

Next, a passivation film 1009 made of an insulating material is formed on the absorption film 1008. Note that E
Since the L element is vulnerable to oxygen, moisture, and the like, it is desirable to continuously perform the steps from the formation of the EL layer to the formation of the passivation.

Finally, the FPC 1013 is attached to complete a passive light emitting device.

The structure of this embodiment can be implemented by freely combining with any of the structures of Embodiments 1 and 2.

[Embodiment 4] In this embodiment, a method for preventing the invasion of oxygen, moisture and the like from the outside after the sealing structure of the EL element is formed will be described.

FIG. 10A shows an EL having a sealing structure.
A sectional view in a film forming chamber 1109 for depositing a metal film on a panel is simplified. Note that the film formation chamber 1109 is in an atmospheric pressure state filled with an inert gas.

In FIG. 10A, reference numeral 1101 denotes a substrate. An EL element 1102 is formed on the substrate.
104 is formed so as to cover the EL element 1102. Further, a passivation film 1105 is formed on the connection wiring 1103 and the absorption film from the EL element 1102, and these are sealed with a sealing substrate 1108 and a sealant 1106. Note that the passivation film 110
5 and the region sealed by the sealing substrate 1108
107. The state formed so far is referred to as an EL panel in this specification.

The EL panel is a gate 1 of the film forming chamber 1109.
It is put in and out from 110. Then, the substrate is provided on an auxiliary table 1111 via a mask 1118 with the side on which the EL element is formed on the substrate facing down.

The deposition source 1112 in the film forming chamber 1109 is provided with a low melting point metal for forming a metal film.
This is because damage to the sealant 1106 used for sealing due to heat during film formation is considered. Specifically, a material such as aluminum or magnesium is desirable.

Then, vapor deposition is performed under atmospheric pressure.
Note that at the time of vapor deposition, a mask 1118 is provided, and the connection wiring 1103 covered with the passivation film 1105 is provided.
In addition, a metal film is not formed in an unnecessary range. In addition, the evaporation source 111 is used to adjust the evaporation position.
2 may be moved, or the position and angle of the EL panel may be changed.

As shown in FIG. 10B, according to the present embodiment, the sealing portion of the EL panel with the sealant is
It can be formed so as to be covered with 116. Also, 11
13 is an anode, 1114 is an EL layer, 1115 is a cathode, 11
17 is an insulator. Further, in this embodiment, since the metal film can be formed under the atmospheric pressure, E
A problem associated with a change in pressure in the sealing structure when the L panel is taken out into the atmosphere can be prevented.

The structure of this embodiment can be implemented by freely combining with any of the structures of the first to third embodiments.

[Embodiment 5] In this embodiment, an example of a film forming apparatus used in performing film formation and sealing processing from the formation of an EL layer to the formation of a sealing structure in each of the above embodiments will be described. .

A thin film forming apparatus according to the present invention will be described with reference to FIG. In FIG. 13, reference numeral 1401 denotes a load chamber for loading or unloading a substrate, which is also called a load lock chamber. Here, a carrier 1402 on which a substrate is set is arranged. Note that the load chamber 1401 may be distinguished between the substrate loading and the substrate unloading. In this embodiment, a substrate in which the anode of the EL element is formed on the substrate is set.

Reference numeral 1403 denotes a transfer chamber (A) including a mechanism 1405 for transferring the substrate 1404 (hereinafter, referred to as a transfer mechanism (A)). A robot arm or the like for handling a substrate is a type of the transport mechanism (A) 1405.

The transfer chamber (A) 1403 is connected to a plurality of film forming chambers and processing chambers via a gate.
Since each of the film forming chamber, the transfer chamber, and the processing chamber is completely shut off by the gate, a hermetically sealed space can be obtained. The transfer chamber (A) 1
Reference numeral 403 denotes a transfer chamber (A) 1403 because of a reduced-pressure atmosphere.
All of the processing chambers directly connected to are provided with an exhaust pump (not shown).

As an exhaust pump, an oil rotary pump, a mechanical booster pump, a turbo molecular pump or a cryopump can be used, but a cryopump effective for removing water is preferable.

First, the film forming chamber (A) shown at 1407 will be described. The film formation chamber (A) 1407 is connected to the transfer chamber (A) 1403 by a gate 1406b and is a film formation chamber for performing film formation by an evaporation method. In addition, as a vapor deposition method, a method by resistance heating (RE method: Resistivity)
Evaporation method) and electron beam method (EB method: Electr
onBeam method) can be used.
The case of performing the vapor deposition by the E method will be described.

The film is formed in the film formation chamber (A) 1407 by a hole injection layer, a hole transport layer,
A light emitting layer, an electron transport layer, and an electron injection layer.

An EL material to be used for film formation is previously provided in a sample boat provided in the film formation chamber (A), and vapor deposition is performed by heat generated by applying a voltage to the sample boat. Since the EL material is extremely weak to moisture,
During the formation of the EL layer, the pressure in the film formation chamber (A) 1407 needs to be constantly maintained in a vacuum state. Film formation chamber (A) 140
7, except that the substrate is moved into and out of the gate 1406b.
It is preferable to completely shut off from the transfer chamber (A) 1405 by using and control the vacuum state in the film formation chamber. At this time, the film forming pressure needs to be 1 × 10 ⁻⁶ to 1 × 10 ⁻⁵ Torr.

The film forming chamber (A) 1407 is provided with means for observing the state of film formation of the EL material from outside the apparatus.
Windows may be provided on the side surfaces of the film formation chamber. Thereby, it can be confirmed that the film formation is performed normally. In addition, the film forming chamber (A) 140
Reference numeral 7 is provided with a plurality of sample boats (not shown) provided with an EL material, so that a plurality of layers forming an EL layer can be formed. Specifically, it is preferable to provide 1 to 8 types.

In the case where an EL layer is formed by spin coating, an EL solution containing an EL material is applied to a substrate in a film forming chamber (B) 1410 provided with a spin coater. A film containing a material is formed. Note that in this embodiment, the film is formed in the film formation chamber (B) 1410 when a high molecular EL material is formed. However, in some cases, a film may be formed in the film formation chamber (B) 1410 when a low-molecular EL material is dissolved in a solvent to form a film.

[0177] The film formation chamber (B) 1410 provided with a spin coater is connected to the transfer chamber (B) 1414 via a gate 1406g. In addition, the film forming chamber (B)
The substrate subjected to the film formation processing in 1410 is transferred to the transfer chamber (B).
1414 through a gate 1406h through a firing chamber 141
1 and fired.

Then, the substrate after the firing treatment is transferred to the pressure adjustment chamber 1408 connected to the transfer chamber (B) via the gate 1406f. The substrate is in the pressure adjustment chamber 140
After being transferred to the gate 8, the gate 1406f is closed, and the inside of the pressure adjustment chamber 1408 is reduced in pressure.

When the pressure in the pressure adjustment chamber 1408 becomes equal to or less than a certain reduced pressure, the gate 1406d opens and the substrate is taken out by the transport mechanism (A) 1405.

When the EL layer is formed, the transfer chamber (A)
A film formation chamber (C) connected to 1403 by a gate 1406c
The substrate is transported to 1412. The film formation chamber (C) is a film formation chamber for forming a film by an evaporation method. In this embodiment,
In the same manner as in the deposition chamber (A) 1407 for depositing an EL layer, evaporation is performed by the RE method. Then, in the film formation chamber (C) 1412, an insulating film such as a barrier film, an absorption film, and a passivation film formed over the EL layer is formed by an evaporation method.

Also, a plurality of sample boats (not shown) are provided in the film forming chamber (C) 1412. Specifically, an insulating material such as silicon nitride or silicon oxide, which is a material for forming a barrier film and a passivation film, and a film forming material such as barium for forming an absorption film are provided.

After the formation of the passivation film, the substrate is transferred to the sealing chamber 1413 connected to the transfer chamber (A) 1403 via the gate 1406e. In addition,
In the sealing chamber 1413, a process for finally sealing the EL element in a closed space is performed. Specifically, a process of sealing the EL element formed on the substrate with a sealing substrate and a sealant is performed.

Materials such as glass, ceramics and metal can be used for the sealing substrate, and thermosetting resins and ultraviolet-curing resins can be used as the sealant.

Note that the sealing chamber 1413 has a function of performing a heat treatment or an ultraviolet irradiation treatment.

Then, in the sealing chamber 1413, the substrate subjected to the sealing process returns to the load chamber 1401 again via the gate 1406a by the transport mechanism (A) 1405.

The structure of this embodiment can be implemented by freely combining with any of the structures of Embodiments 1 to 4.

[Embodiment 6] Various electric appliances can be manufactured by incorporating a light emitting device formed by implementing the present invention. Examples of the electric appliance of the present invention include a video camera, a digital camera, a goggle-type display (head-mounted display), a navigation system,
Examples include an audio device, a notebook personal computer, a game device, a portable device (a mobile computer, a mobile phone, a portable game device or an electronic book), and an image reproducing device provided with a recording medium. Specific examples of these electric appliances are shown in FIGS.

FIG. 14A shows an EL display.
A housing 2001, a support base 2002, and a display unit 2003 are included. The display device is manufactured by using the light emitting device of the present invention for the display portion 2003. In the case where a light-emitting device having an EL element is used for the display portion 2003, a thin display portion can be provided without a backlight because the EL element is a self-luminous type.

FIG. 14B shows a video camera, which includes a main body 2101, a display portion 2102, an audio input portion 2103, operation switches 2104, a battery 2105, and an image receiving portion 210.
6 inclusive. It is manufactured by using the light emitting device of the present invention for the display portion 2102.

FIG. 14C shows a digital camera, which includes a main body 2201, a display section 2202, an eyepiece section 2203, and operation switches 2204. It is manufactured by using the light emitting device of the present invention for the display portion 2202.

FIG. 14D 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 portion (a) 2305 mainly displays image information, and the display portion (b) mainly displays character information. The display portion (a) 2305 is manufactured by using the light emitting device of the present invention for these display portions (a) and (b). You. In addition,
The image reproducing device provided with the recording medium may include a CD reproducing device, a game device, and the like.

FIG. 14E 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. It is manufactured by using the light emitting device of the present invention 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. 14F shows a personal computer, which includes a main body 2501, a housing 2502, a display portion 2503,
A keyboard 2504 is included. It is manufactured by using the light emitting device of the present invention for the display portion 2503.

In addition, the above-mentioned electric appliances are available on the Internet or C
Information distributed through an electronic communication line such as an ATV (cable television) is often displayed, and in particular, opportunities to display moving image information are increasing. By using a light-emitting device having an EL element in a display portion, a moving image can be displayed without delay because the response speed of the EL element is extremely high.

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 character information such as a mobile phone or an audio device, the character information is driven by the light emitting portion with the non-light emitting portion as a background. It is desirable.

FIG. 15A shows a portable telephone, and the main body 26 is provided.
01, audio output unit 2602, audio input unit 2603, display unit 2604, operation switch 2605, antenna 2606
including. It is manufactured by using the light emitting device of the present invention for the display portion 2604. Note that the display portion 2604 can reduce power consumption of the mobile phone by displaying characters in the light-emitting portion on the background of the non-light-emitting portion.

FIG. 15B also shows a mobile phone.
Unlike (A), it is a two-fold type. Body 26
11, an audio output unit 2612, an audio input unit 2613, a display unit a2614, a display unit b2615, and an antenna 2616. Note that this type of mobile phone does not have an operation switch, but one of the display units a and b has a display unit as shown in FIGS. 15C, 15D, and 15E. It displays the character information and provides its function. The other display unit mainly displays image information. It should be noted that the light emitting device of the present invention has a display portion a
2614 or the display portion b2615.

In the case of the mobile phone shown in FIGS. 15A and 15B, a sensor (CMOS sensor) is built in a light emitting device used for a display portion with a CMOS circuit, and a fingerprint or palm is read to allow the user to read the user. It can also be used as an authentication system terminal for authentication. In addition, external brightness (illuminance)
Can be read to emit light so that information can be displayed with the set contrast.

Further, in FIG. 15A, the power consumption can be reduced by lowering the luminance when the operation switch 2605 is used and increasing the luminance when the operation switch is used. In addition, the display unit 26
The power consumption can also be reduced by increasing the brightness of 04 and lowering it during a call. In addition, when the device is continuously used, a function of turning off the display by time control unless resetting is provided, so that power consumption can be reduced. Note that these may be manually controlled.

FIG. 15F shows a sound reproducing device, specifically, an audio for vehicle, which comprises a main body 2621 and a display portion 262.
2, including operation switches 2623 and 2624. It is manufactured by using the light emitting device of the present invention for the display portion 2622. In this embodiment, the in-vehicle audio is shown, but the present invention may be applied to a portable or home-use audio reproducing apparatus. Note that the display portion 2622 can suppress power consumption by displaying white characters in the light-emitting portion on the background of the non-light-emitting portion. This is particularly effective in a portable sound reproducing device.

Further, in the portable electric appliance shown in this embodiment, as a method for reducing power consumption, a sensor unit for sensing external brightness is provided, and when used in a dark place, a display unit is provided. To add a function such as lowering 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, any configuration shown in the first to fifth embodiments may be applied to the electric appliance of the present embodiment.

[0203]

According to the present invention, since a metal having absorptivity to substances such as oxygen and moisture is provided as a film on the EL element in the sealed space, it is possible to provide the space with an absorbing function. The feature is that it becomes easier than before and the sealing structure can be manufactured without invading oxygen or moisture into the space because the absorbing film can be formed continuously after the EL element is formed. is there.

[Brief description of the drawings]

FIG. 1 illustrates the present invention.

FIG. 2 illustrates an element structure of an EL element according to the present invention.

FIG. 3 is a diagram showing an effect obtained by implementing the present invention.

FIG. 4 is a diagram illustrating a manufacturing process of a pixel TFT and a TFT of a driver circuit.

FIG. 5 is a diagram illustrating a manufacturing process of a pixel TFT and a TFT of a driver circuit.

FIG. 6 is a diagram illustrating a manufacturing process of a pixel TFT and a TFT of a driver circuit.

FIG. 7 is a diagram illustrating a manufacturing process of a pixel TFT and a TFT of a driver circuit.

8A and 8B illustrate a top view and a sealing structure of a light-emitting device.

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

FIG. 10 illustrates a state of sealing a light-emitting device.

FIG. 11 is a photograph showing a state of deterioration of an EL layer.

FIG. 12 is a photograph showing a state of deterioration of an EL layer.

FIG. 13 is a diagram of a film forming apparatus used for forming a light emitting device of the present invention.

FIG. 14 illustrates a specific example of an electric appliance.

FIG. 15 illustrates a specific example of an electric appliance.

FIG. 16 illustrates a conventional example.

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Claims (7)

[Claims] 1. A light emitting device having an EL element on a substrate, wherein an absorption film is formed on the EL element, and the EL element is sandwiched between the substrate and the absorption film. apparatus. 2. A light emitting device having an EL element on a substrate, wherein an absorption film is formed on the EL element, and
A light-emitting device, wherein the element is provided in a space surrounded by the substrate, the sealing substrate, and a sealant. 3. The light emitting device according to claim 2, wherein the sealant is provided at a position not overlapping with the absorbing film. 4. A light emitting device having an EL element on a substrate, wherein the EL element comprises an anode, an EL layer, and a cathode, wherein an absorption film is formed on the cathode.
A light-emitting device, wherein the element is sandwiched between the substrate and the absorbing film. 5. The light emitting device according to claim 4, wherein an absorption film is formed on the cathode, and the EL layer, the cathode, and the absorption film are continuously formed in an inert gas atmosphere. A light-emitting device, characterized in that: 6. A light emitting device having a TFT on a substrate, comprising: an EL element electrically connected to the TFT;
A light-emitting device, wherein an absorption film is formed on the EL element, and the EL element is sandwiched between the substrate and the absorption film. 7. The light emitting device according to claim 1, wherein said absorbing film contains an alkaline earth metal.