JP2004063461A - Light emitting device and manufacturing method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light emitting device configured to increase light emitting amount extracted in one direction from a light emitting element. <P>SOLUTION: An etching process is performed in such a manner that a curved surface with a radius of curvature is formed at a top end part of an insulating matter 19, an inclined surface is formed by exposing a part of a first electrode 18c in matching to the curved surface, and a first electrode 18b is exposed in an area to be a light emitting area. A light emitting from an organic compound layer 20 is reflected from the inclined surface of the first electrode 18c, and a total extracted amount of the light in a direction of an arrow shown in a figure is increased. Furthermore, a light absorption multi-layered film 24 is formed on the first electrode 18c except the area to be the light emitting area. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a light-emitting device using a light-emitting element which obtains fluorescence or phosphorescence by applying an electric field to an element provided with a film containing an organic compound between a pair of electrodes, and a method for manufacturing the light-emitting device. Note that a light-emitting device in this specification refers to an image display device, a light-emitting device, or a light source (including a lighting device). Further, a module in which a connector, for example, an FPC (Flexible printed circuit) or TAB (Tape Automated Bonding) tape or a TCP (Tape Carrier Package) is attached to the light emitting device, or a module in which a printed wiring board is provided at the tip of the TAB tape or TCP. Alternatively, all the modules in which an IC (integrated circuit) is directly mounted on a light emitting element by a COG (Chip On Glass) method are included in the light emitting device.
[0002]
[Prior art]
Light-emitting elements using a layer containing an organic compound having characteristics such as thinness and lightness, high-speed response, and DC low-voltage driving as a light-emitting body are expected to be applied to a next-generation flat panel display. In particular, a display device in which light-emitting elements are arranged in a matrix is considered to be superior to a conventional liquid crystal display device in that the display device has a wide viewing angle and excellent visibility.
[0003]
The light-emitting mechanism of a light-emitting element is such that by applying a voltage across a layer containing an organic compound between a pair of electrodes, electrons injected from a cathode and holes injected from an anode are emitted at a light emission center in the organic compound layer. It is said that they recombine to form molecular excitons, which emit energy when the molecular excitons return to the ground state to emit light. Singlet excitation and triplet excitation are known as excited states, and light emission is considered to be possible through either excited state.
[0004]
For a light-emitting device formed by arranging such light-emitting elements in a matrix, a driving method such as passive matrix driving (simple matrix type) and active matrix driving (active matrix type) can be used. However, when the pixel density increases, it is considered that an active matrix type in which a switch is provided for each pixel (or one dot) is advantageous because it can be driven at a low voltage.
[0005]
As a layer containing an organic compound (strictly speaking, a light-emitting layer) which can be said to be the center of a light-emitting element, a low-molecular material and a high-molecular (polymer) material have been studied, respectively. Also, polymer materials that are easy to handle and have high heat resistance have attracted attention.
[0006]
In an active matrix light-emitting device, an electrode electrically connected to a TFT on a substrate is formed as an anode, a layer containing an organic compound is formed on the anode, and a cathode is formed on the layer containing the organic compound. Is formed, and light generated in the layer containing the organic compound is extracted from the anode, which is a transparent electrode, toward the TFT.
[0007]
However, in this structure, there has been a problem that the aperture ratio is limited by the arrangement of the TFTs and the wirings in the pixel portion in order to improve the resolution.
[0008]
[Problems to be solved by the invention]
Therefore, in the present invention, an electrode on the TFT side electrically connected to the TFT on the substrate is formed as an anode (or a cathode), a layer containing an organic compound is formed on the anode (or a cathode), and the organic compound is formed. An active matrix light-emitting device having a light-emitting element having a structure in which a cathode (or an anode) which is a transparent electrode is formed over a layer containing the light-emitting element (hereinafter, referred to as a top emission structure) is manufactured.
[0009]
In the top emission structure, as compared with the bottom emission structure, the number of material layers through which light emitted from the layer containing an organic compound passes can be reduced, and stray light between material layers having different refractive indexes can be suppressed.
[0010]
Further, not all of the light generated in the layer containing the organic compound is extracted from the cathode (or the anode), which is a transparent electrode, toward the TFT. For example, the light is also emitted in the lateral direction (the direction parallel to the substrate surface). However, as a result, the light emitted in the lateral direction is not extracted, resulting in a loss. Further, irradiation of the active layer of the TFT with such stray light affects the electrical characteristics of the TFT and is one of the causes of deterioration. Therefore, an object of the present invention is to provide a light-emitting device having a structure in which stray light is prevented and a light emission amount extracted in one direction is increased, and a method for manufacturing the light-emitting element.
[0011]
Further, in the top emission structure, there is a problem that the film resistance of the transparent electrode is increased. In particular, when the thickness of the transparent electrode is reduced, the film resistance further increases. When the film resistance of the transparent electrode serving as a cathode (or an anode) is increased, a voltage drop causes an in-plane potential distribution to become non-uniform, which causes a problem that the luminance of the light emitting element varies. Therefore, an object of the present invention is to provide a light-emitting device having a structure in which the film resistance of a transparent electrode in a light-emitting element is reduced, and a manufacturing method thereof. Then, it is an object to provide an electric appliance using such a light emitting device as a display portion.
[0012]
[Means for Solving the Problems]
The present invention includes a metal film covered with a light-absorbing multilayer film by continuously forming a stack of metal films and a light-absorbing multilayer film (hereinafter, referred to as a light-absorbing multilayer film), and performing patterning. After forming a first electrode and forming an insulator (referred to as a bank or a partition) covering an end portion of the first electrode, etching is performed in a self-aligned manner using the insulator as a mask. Part of the first electrode is etched and the center of the first electrode is thinly etched. By this etching, the central part of the first electrode is made thin and flat, and the peripheral part of the first electrode covered with the insulator is made thick, that is, concave. Note that a light-absorbing multilayer film is provided over the first electrode covered with the insulator, and absorbs external light. Then, a layer containing an organic compound and a second electrode are formed at least over a central portion of the first electrode to complete a light-emitting element.
[0013]
According to the present invention, light emitted in a horizontal direction is reflected or condensed on a slope formed on a first electrode to increase the amount of light emitted in a certain direction (a direction passing through a second electrode).
[0014]
Therefore, the slope portion is preferably made of a material mainly reflecting a metal that reflects light, for example, aluminum, silver, or the like, and the central portion in contact with the layer containing an organic compound is preferably an anode material having a large work function (or , A cathode material having a small work function). When the portion to be the slope is made of a material mainly containing aluminum, silver, or the like, it reflects light from the outside. Therefore, it is preferable that the portion other than the slope is covered with a material having a low reflectance, preferably a light-absorbing multilayer film. .
[0015]
To form a light-absorbing multilayer film, for example, a silicon nitride film and a metal nitride film (typically, a titanium nitride film) are formed on a metal layer having high reflectivity (typically, a metal layer mainly containing aluminum). , A tantalum nitride film, etc.) and a silicon nitride film may be laminated with an appropriate thickness, and when light is incident from the outside, the light is reduced by optical interference absorption caused between these layers. The location where the light absorbing multilayer film is provided does not overlap with the light emitting region.
[0016]
In addition, the presence of the slope formed in the first electrode prevents light emitted from the light emitting element (including light emitted in the horizontal direction) from reaching the TFT.
[0017]
Configuration 1 of the invention disclosed in this specification includes:
A first electrode connected to the thin film transistor over a substrate having an insulating surface;
An insulator covering an end of the first electrode;
A light-emitting element including a layer containing an organic compound in contact with the first electrode and a second electrode in contact with the layer containing the organic compound,
The first electrode has an inclined surface facing a central portion of the first electrode, and the inclined surface reflects light emitted from the layer containing the organic compound,
The light-emitting device is characterized in that a light-absorbing multilayer film from the outside is provided in a portion of the first electrode covered with the insulator.
[0018]
In addition, Configuration 2 of another invention is as follows.
A first electrode connected to the thin film transistor over a substrate having an insulating surface;
An insulator covering an end of the first electrode;
A light-emitting element including a layer containing an organic compound in contact with the first electrode and a second electrode in contact with the layer containing the organic compound,
A central portion of the first electrode has a concave shape with a smaller thickness than an end portion, and a light absorbing multilayer film from the outside is provided on a portion of the first electrode covered with the insulator. It is a light emitting device characterized by being used.
[0019]
In addition, Configuration 3 of another invention is as follows.
A first electrode connected to the thin film transistor over a substrate having an insulating surface;
An insulator covering an end of the first electrode;
A light-emitting element including a layer containing an organic compound in contact with the first electrode and a second electrode in contact with the layer containing the organic compound,
The first electrode has a multi-layer structure, and has a larger number of layers at the end than at the center of the first electrode, and has an end (the first electrode portion covered with the insulator). The light-emitting device is provided with an external light-absorbing multilayer film provided thereon.
[0020]
In addition, a multilayer film that absorbs external light is provided also on wirings and electrodes formed in the same process.
A first electrode connected to the thin film transistor over a substrate having an insulating surface;
An insulator covering an end of the first electrode;
A light-emitting element including a layer containing an organic compound in contact with the first electrode and a second electrode in contact with the layer containing the organic compound,
The wiring or the electrode formed on the same layer as the first electrode has a multilayer structure, and is provided with an external light absorbing multilayer film.
[0021]
Further, according to the present invention, when an organic compound film made of a polymer is formed by a coating method, the shape of an insulator (referred to as a bank, a partition, a barrier, a bank, etc.) provided between pixels in order to eliminate poor coverage or the like. Add some ingenuity to In each of the above structures, the upper end of the insulator has a curved surface having a radius of curvature, and the radius of curvature is 0.2 μm to 3 μm. Further, the taper angle of the insulator may be 35 ° to 70 °.
[0022]
By providing a curvature, the step coverage can be improved, and a film can be formed even if a layer containing an organic compound to be formed later is extremely thin.
[0023]
In each of the above structures, the first electrode has an inclined surface facing a central portion of the first electrode, and an inclination angle (also referred to as a taper angle) exceeds 50 °, less than 60 °, and Preferably, it is 54.7 °. The angle of inclination, the material and thickness of the organic compound layer, or the material and thickness of the second electrode are appropriately adjusted so that the light reflected on the inclined surface of the first electrode is not dispersed between the layers or becomes stray light. It is necessary to set the film thickness.
[0024]
Here, a simulation was performed according to the following procedure for an increase in the extraction efficiency when the structure of the present invention was used.
[0025]
First, the effect of the structure of the present invention was estimated by treating EL light emission (light emission from a layer containing an organic compound) as rays uniformly emitted in all directions and treating them geometrically.
[0026]
As a basic law, Snell's law (refractive index n _i Angle θ from the film _i And the refractive index n _i Angle θ to the film _j When transmitted through, n _i ・ Sin θ _i = N _j ・ Sin θ _j ) And the total reflection condition (θ in Snell's law) _j = 90 ° when θ _i Is exceeded (critical angle), all light rays are reflected in a path symmetrical to the normal. ).
[0027]
First, the conditions under which light rays are emitted from the parallel multilayer film to the atmosphere are considered as follows.
[0028]
As shown in FIG. 12, when the path of a light beam that passes through a parallel multilayer film from a layer containing an organic compound (EL layer) and exits to the atmosphere is seen, the relationship (n _el sinθel = n ₁ .Sin.theta.1 =... = Sin.theta.air). Note that n _el , N ₁ Denotes the refractive index of a layer containing an organic compound, and the refractive index of the layer thereon (the first layer in FIG. 12), and the refractive index of air is 1. If θair is 90 ° or less, θ1 etc is less than 90 °. (Θel when θair is 90 ° is θc). As long as the light beam enters the atmosphere, it will not be totally reflected at the internal interface. Therefore, the condition of θel at which the light beam enters the atmosphere is 0 <θel <θc.
[0029]
Further, in the structure shown in FIG. 13, there are the following two kinds of paths for the light beam emitted to the atmosphere. That is, there is a case where the light enters the atmosphere without being reflected by the slope (path 1), and a case where the light enters the atmosphere via the reflection of the slope (path 2). In the case of the path 1, since the path of the light beam is the same as that in the case of transmitting the light through the simple parallel multilayer film described above, the condition for exit to the atmosphere is 0 <θel <θc. In the case of the path 2, it is understood that the angle of incidence in the case of the path 1 is the same as that obtained by changing the incident angle from θel to θel ± θt by re-observing the slope portion as shown in FIG. 14. Thus, the condition of being in the atmosphere can be expressed as 0 <θel ± θt <θc. However, since total reflection must be performed in the horizontal portion, θc <θel, so that only 0 <θel−θt <θc. That is, as shown in FIG. 14, there are two types of incidence on the slope portion with respect to one θel, but only one of them can be transmitted.
[0030]
The light emission extraction efficiency is considered as follows. The extraction efficiency is defined as the ratio of the angle range in which a ray starting from the midpoint in the direction perpendicular to the substrate in the layer containing the organic compound to the atmosphere occupies the entire solid angle.
[0031]
The ratio of light emitted from the range forming an angle of θ to θ + dθ with the normal is 2πsin θdθ / 4π since it is replaced by the area ratio on the unit spherical surface centered on the light emitting point as shown in FIG. Therefore, if the range of θ is θ1 to θ2, the light extraction efficiency is 2π (−cosθ1 + cosθ2) / 4π as a result of integrating this equation. Thus, the light extraction efficiency can be obtained from the allowable range of θel considered two-dimensionally.
[0032]
Where n _air = 1, n _el = 1.73 (typical EL material Alq ₃ Is the value in the case where is used, θc = 35.31 ° from sin θc = 1 / 1.73. In the case of the path 1, the emission angle range is 0 <θel <θc from 0 <θel <θc, and the extraction efficiency is 18.4% from −cos θc + cos0 = 0.184.
[0033]
In the case of the path 2, since it is necessary to be totally reflected at the horizontal part, it is necessary that θel> θc. 0 <θel−θt <θc⇔θt <θel <θc + θt, and in the case of θt <θc, the lower limit of the emitted θt <θel <θc + θt changes, and the emission angle range becomes θc <θel <θc + θt. Thus, the extraction efficiency is (-cos (θc + θt) + cosθc) / 2. When θc + θt> π / 2, the upper limit of θt <θel <θc + θt changes, and the emission angle range becomes θt <θel <π / 2, and the extraction efficiency is (−cosπ / 2 + cosθt) / 2. It becomes. In other cases (θc <θt <π / 2−θc), θt <θel <θc + θt holds as it is, the emission angle range becomes θt <θel <θc + θt, and the extraction efficiency is (−cos (θc + θt) + cos θt) / 2.
FIG. 2B shows the relationship between the increase in light extraction efficiency due to the paths 1 and 2 due to the presence of the slope formed in the first electrode and the taper angle θt of the slope in the present invention. . In FIG. 2B, a peak corresponding to an increase in light extraction efficiency exists at θt = 54.69 °. Note that the result of FIG. 2B is a simulation result that does not consider light absorption and interference in the film, and assumes that the light emitting point is the center of the EL layer.
[0034]
FIG. 18 shows the reflectance of an aluminum film containing a small amount of Ti and the reflectance of a TiN film (100 nm).
[0035]
In each of the above structures, the second electrode is a conductive film that transmits light, for example, a thin metal film, a transparent conductive film, or a stacked layer thereof.
[0036]
Further, in each of the above structures, the first electrode has a concave shape, and the concave shape is formed in a self-aligned manner using the insulator as a mask. Therefore, there is no increase in the number of masks in forming the concave shape of the first electrode. In addition, the concave end (the upper end of the inclined portion) of the first electrode and the side surface of the insulator substantially coincide with each other. It is desirable that the inclination angle on the side surface of the object is the same.
[0037]
Further, in each of the above structures, the first electrode is an anode, and the second electrode is a cathode. Alternatively, in each of the above structures, the first electrode is a cathode and the second electrode is an anode.
[0038]
In each of the above structures, the light-absorbing multilayer film provided on a peripheral portion (a portion covered with an insulator) of the first electrode includes at least one nitride insulating film having a light-transmitting property. And Specifically, the light-absorbing multilayer film provided on a peripheral portion (a portion covered with an insulator) of the first electrode includes a light-transmitting film, a light-absorbing film, and a light-absorbing film. A film having at least a three-layer structure with a film having a light-transmitting property; ₂ O ₃ , SiO ₂ , ZrO ₂ , HfO ₂ , Sc ₂ O ₃ , TiO ₂ , ITO, or ZnO.
[0039]
Alternatively, in each of the above structures, the light-absorbing multilayer film provided on a peripheral portion (a portion covered with an insulator) of the first electrode may be a multilayer film including at least one light-transmitting nitride insulating film. do it. With a stack of a silicon nitride film, a titanium nitride film, and a silicon nitride film, the reflectance can be 5% or less. The same effect can be obtained by using a brown or black metal film such as a tantalum nitride film instead of titanium nitride.
[0040]
In each of the above structures, the other film that partially absorbs light includes Al, Cu, Au, Mo, Ni, Pt, Rh, Ag, W, Cr, Co, Si, Zr, Ta, Inconel, or What is necessary is just to make into the film | membrane which contains at least one layer which consists of nichrome.
[0041]
In each of the above structures, the layer containing the organic compound is a material that emits white light, and a light-emitting device combined with a color filter provided in a sealing material, or the layer containing the organic compound is The light-emitting device is a material which emits monochromatic light and is combined with a color conversion layer or a coloring layer provided in a sealing material.
[0042]
Further, according to the present invention, after forming the concave portion of the first electrode, an auxiliary wiring (or a wiring, also referred to as a third electrode) is formed on an insulator arranged between the pixel electrodes by an evaporation method using an evaporation mask, The film resistance of the second electrode (electrode that transmits light) serving as a cathode may be reduced. In addition, a feature of the present invention is that a lead wiring is formed using the auxiliary wiring and connected to another wiring existing in a lower layer.
[0043]
The configuration of the invention for realizing each of the above configurations 1, 2, 3, and 4 is as follows:
An anode, a layer containing an organic compound in contact with the anode, and a method for manufacturing a light-emitting device including a light-emitting element having a cathode in contact with the layer containing the organic compound,
A step of continuously forming a stack of a metal film and a light-absorbing multilayer film without touching the atmosphere,
Forming an insulator covering an end of the first electrode made of the metal film;
Using the insulator as a mask, performing etching, and thinning the center of the first electrode so that a slope is exposed along the edge of the first electrode;
Forming a film containing an organic compound;
Forming a second electrode made of a light-transmitting metal thin film on the film containing the organic compound.
[0044]
Further, in the structure according to the above manufacturing method, the light-reflecting metal film has a stack of a metal film that reflects light and a metal film serving as an etching stopper, and the metal film that reflects light is etched. It is characterized in that the material is exposed.
[0045]
Further, in the above structure, the first electrode is an anode, and is formed of a metal layer having a larger work function than the second electrode.
[0046]
In the structure of the above manufacturing method, the step of continuously forming a stack of the metal film (first electrode) and the light-absorbing multilayer film is formed by a sputtering method.
[0047]
In the structure of the above manufacturing method, the insulator covering the end of the first electrode has a curved surface having a radius of curvature at an upper end, and the radius of curvature is 0.2 μm to 3 μm. It is characterized by.
[0048]
Note that the EL element includes a layer containing an organic compound capable of obtaining luminescence (Electro Luminescence) generated by application of an electric field (hereinafter, also referred to as an EL layer), an anode, and a cathode. The luminescence in the layer containing an organic compound includes light emission when returning from a singlet excited state to a ground state (fluorescence) and light emission when returning from a triplet excited state to a ground state (phosphorescence). The light-emitting device manufactured by the manufacturing apparatus and the film formation method can be applied to the case of using either light emission.
[0049]
A light-emitting element (EL element) including an EL layer has a structure in which an EL layer is sandwiched between a pair of electrodes. The EL layer usually has a stacked structure. Typically, a laminated structure of “hole transport layer / light-emitting layer / electron transport layer” is given. This structure has a very high luminous efficiency, and most light-emitting devices currently under research and development adopt this structure.
[0050]
In addition, a hole injection layer / a hole transport layer / a light emitting layer / an electron transport layer, or a hole injection layer / a hole transport layer / a light emitting layer / an electron transport layer / an electron injection layer are stacked in this order on the anode. The structure is also good. The light emitting layer may be doped with a fluorescent dye or the like. Further, these layers may be formed entirely using a low molecular material, or may be formed entirely using a high molecular material. In this specification, all layers provided between a cathode and an anode are collectively referred to as an EL layer. Therefore, the hole injection layer, the hole transport layer, the light emitting layer, the electron transport layer, and the electron injection layer are all included in the EL layer.
[0051]
In the light emitting device of the present invention, a driving method for screen display is not particularly limited, and for example, a dot sequential driving method, a line sequential driving method, a plane sequential driving method, or the like may be used. Typically, a line-sequential driving method is used, and a time-division grayscale driving method or an area grayscale driving method may be used as appropriate. Further, the video signal input to the source line of the light emitting device may be an analog signal or a digital signal, and a drive circuit or the like may be appropriately designed in accordance with the video signal.
[0052]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described below.
[0053]
FIG. 1A is a cross-sectional view (a part of one pixel) of an active matrix light-emitting device. Here, a light-emitting element in which a layer containing an organic compound formed of a polymer material that emits white light is used as a light-emitting layer will be described as an example.
[0054]
In FIG. 1A, a TFT (p-channel TFT) provided on a substrate 10 having an insulating surface is an element for controlling a current flowing to an EL layer 20 which emits white light, and 13 and 14 are source regions. Or it is a drain region. A base insulating film 11 (here, a lower layer is a nitride insulating film and an upper layer is an oxide insulating film) is formed on the substrate 10, and a gate insulating film 12 is provided between the gate electrode 15 and the active layer. ing. 16a is an interlayer insulating film made of an organic material or an inorganic material, and 16b is a protective film made of a silicon nitride film, a silicon nitride oxide film, aluminum nitride, or aluminum nitride oxide. Although not shown here, one pixel is provided with one or more TFTs (n-channel TFTs or p-channel TFTs). Although a TFT having one channel formation region is described here, the present invention is not particularly limited thereto, and a TFT having a plurality of channels may be used.
[0055]
Reference numerals 18a to 18c denote first electrodes, ie, anodes (or cathodes) of the light emitting elements, and reference numeral 21 denotes a second electrode formed of a conductive film, ie, cathodes (or anodes) of the light emitting elements. The region that actually functions as the anode is 18b. Here, a titanium film 18a, a titanium nitride film 18b, and a film containing aluminum as a main component are sequentially stacked as 18c, and 18b in contact with the layer 20 containing an organic compound functions as an anode. Further, the power supply line 17 is formed in the same laminated structure. The stacked structure includes a film containing aluminum as a main component, can be a low-resistance wiring, and the source wiring 22 and the like are formed at the same time.
[0056]
In order to prevent reflection, a light absorbing multilayer film 24 is provided on 18c. Further, it is provided on the power supply line 17 and the source wiring 22.
[0057]
As the light absorbing multilayer film 24 (a multilayer film that absorbs external light), a typical laminated structure includes a light-transmitting film, a light-absorbing film, and a light-transmitting film. May be formed in a three-layer structure in which are sequentially stacked. As the light-transmitting film, Al ₂ O ₃ , SiO ₂ , ZrO ₂ , HfO ₂ , Sc ₂ O ₃ , TiO ₂ , ITO, or a layer made of ZnO. Other films that partially absorb light include Al, Cu, Au, Mo, Ni, Pt, Rh, Ag, W, Cr, Co, Si, The layer may be made of Zr, Ta, Inconel, or Nichrome.
[0058]
In order to form the layer 20 containing an organic compound later, a film containing nitrogen and a light absorbing multilayer film from the outside will be described here. The following simulation was performed.
[0059]
A silicon nitride film (thickness: 37 nm) and a titanium nitride film (thickness: 66 nm) obtained by a sputtering method using a silicon target in an atmosphere containing nitrogen and argon on a film mainly containing aluminum (thickness: 100 nm). FIG. 16 shows the result of determining the reflectance in a model structure in which a silicon nitride film (thickness: 37 nm) obtained by a sputtering method using a silicon target in an atmosphere containing nitrogen and argon is sequentially stacked. In the simulation, the refractive index of the silicon nitride film in the wavelength range of 300 nm to 800 nm is 2.04 to 2.2, the refractive index of titanium nitride is 1.67 to 2.35, and the refractive index of aluminum is 0.39 to 1.985. Is going. In the visible region, the average reflectance was 3%. Note that the film thickness is not particularly limited, and may be set as appropriate. Further, the optimum film thickness varies depending on the material.
[0060]
Also, FIG. 17 shows the result obtained by performing the same simulation even in the case of covering with a second sealant described later. The reflectance was slightly higher than that in FIG. 16 and could be set to 6% on average. In the case where the silicon nitride film was covered with the second sealant, the optimum thickness of the silicon nitride film was 42 nm.
[0061]
Although an example in which a silicon nitride film, a titanium nitride film, and a silicon nitride film are stacked in this order has been described, for example, a silicon nitride film, a tantalum nitride film, and a silicon nitride film may be stacked in this order. , A titanium nitride film, and an ITO film in this order. It is preferable to stack a silicon nitride film, a titanium nitride film, and an ITO film in this order because a process margin for etching later is large.
[0062]
Further, all of these multilayer films are made of a material that can be formed by a sputtering method, and the first electrode and the light absorbing multilayer film can be continuously formed without exposure to the air. If a nitride film is used as the light absorption layer 24, it also functions as a passivation film. If a nitride film is used as one layer of the light-absorbing multilayer film 24, moisture and oxygen can be blocked, which is suitable for a light-emitting element using the layer 20 containing an organic compound.
[0063]
In order to obtain white light emission, a poly (ethylenedioxythiophene) / poly (styrenesulfonic acid) aqueous solution (PEDOT / PSS) serving as a hole injection layer was applied and baked as the layer 20 containing an organic compound. Thereafter, a luminescent center dye (1,1,4,4-tetraphenyl-1,3-butadiene (TPB), 4-dicyanomethylene-2-methyl-6- (p-dimethylamino-styryl) acting as a luminescent layer -4H-pyran (DCM1), Nile Red, Coumarin 6, etc.)-Doped polyvinyl carbazole (PVK) solution is applied and baked on the entire surface. Note that PEDOT / PSS uses water as a solvent and does not dissolve in an organic solvent. Therefore, when PVK is applied from above, there is no need to worry about re-dissolving. Since PEDOT / PSS and PVK have different solvents, it is preferable not to use the same film forming chamber. Alternatively, the layer 20 containing an organic compound may be a single layer, and a 1,3,4-oxadiazole derivative (PBD) having an electron transporting property may be dispersed in polyvinyl carbazole (PVK) having a hole transporting property. . Further, white light emission can be obtained by dispersing 30 wt% of PBD as an electron transporting agent and dispersing an appropriate amount of four kinds of dyes (TPB, coumarin 6, DCM1, and Nile Red).
[0064]
Alternatively, a film containing an organic compound that emits red light, a film containing an organic compound that emits green light, or a film containing an organic compound that emits blue light can be appropriately selected, and white light emission can be obtained as a whole by overlapping and mixing colors. .
[0065]
Further, CaF is used as the second electrode 21. ₂ Is formed to a thickness of 1 nm to 10 nm by a vapor deposition method, and finally, an Al film is formed to a thickness of about 10 nm by a sputtering method or a vapor deposition method to function as a cathode. The thickness and material of the cathode need to be appropriately selected in order to transmit light from the layer 20 containing an organic compound. Note that in this specification, the term “cathode” includes not only a single-layer film of a material film with a small work function but also a stacked film of a material thin film with a small work function and a conductive film.
[0066]
When an Al film is used as the second electrode 21, a material in contact with the layer 20 containing an organic compound can be formed using a material other than an oxide, so that the reliability of the light-emitting device can be improved. Instead of the Al film, a transparent conductive film (ITO (indium oxide tin oxide alloy), indium oxide zinc oxide alloy (Indium oxide)) is used as the second electrode 21. ₂ O ₃ -ZnO), zinc oxide (ZnO) or the like may be used. In addition, CaF ₂ Instead, a thin metal layer (typically, an alloy such as MgAg, MgIn, or AlLi) may be used.
[0067]
Further, both ends of the first electrodes 18a to 18c and a space between them are covered with an insulator 19 (also called a barrier or a bank). In the present invention, the cross-sectional shape of the insulator 19 is important. By the etching process using the insulator 19 as a mask, concave portions of the first electrodes 18a to 18c are formed. If the upper end of the insulator 19 does not have a curved surface, a film formation defect in which a protrusion is formed at the upper end of the insulator 19 is likely to occur. In view of this, the present invention forms a curved surface having a radius of curvature at the upper end portion of the insulator 19, and a part of the first electrode 18c is exposed in accordance with the curved surface to form a slope, which is used as a light emitting region. Etching is performed so that the first electrode 18b is exposed. Further, a process of flattening the exposed surface of the first electrode 18b may be performed. It is preferable that the radius of curvature at the upper end of the insulator 19 be 0.2 μm to 3 μm. According to the present invention, the coverage of the layer 20 containing the organic compound and the second electrode 21 can be improved. Further, the taper angle on the side surface of the insulator 19 and the taper angle on the slope of the first electrode 18c may both be 55 ° ± 5 °.
[0068]
In the present invention, light emitted from the layer 20 containing an organic compound is reflected by the slope of the first electrode 18c to increase the total amount of light taken out in the direction of the arrow shown in FIG. And
[0069]
In addition, as shown in FIG. 1B, an auxiliary electrode 23 may be provided on the second electrode 21 in order to reduce the resistance of the second electrode (cathode) 21. The auxiliary electrode 23 may be selectively formed by an evaporation method using an evaporation mask.
[0070]
Although not illustrated, a protective film is preferably formed over the second electrode 21 in order to increase the reliability of the light emitting device. This protective film is an insulating film mainly containing silicon nitride or silicon nitride oxide obtained by a sputtering method (DC method or RF method), or a thin film mainly containing carbon. When a silicon target is formed in an atmosphere containing nitrogen and argon, a silicon nitride film can be obtained. Further, a silicon nitride target may be used. Further, the protective film may be formed using a film forming apparatus using remote plasma. In addition, in order to allow light to pass through the protective film, the thickness of the protective film is preferably as small as possible. In the case where a material containing aluminum as a main component is used for the cathode, the property of blocking oxygen and moisture is high.
[0071]
In the present invention, the thin film containing carbon as a main component is a DLC film (Diamond like Carbon) having a thickness of 3 to 50 nm. The DLC film has a short-range order as a bond between carbons, SP ³ Although it has a bond, it has an amorphous structure macroscopically. The DLC film has a composition of 70 to 95 atomic% of carbon and 5 to 30 atomic% of hydrogen, and is very hard and excellent in insulating properties. Such a DLC film is also characterized by a low gas permeability of water vapor and oxygen. Moreover, it is known that it has a hardness of 15 to 25 GPa as measured by a micro hardness tester.
[0072]
The DLC film can be formed by a plasma CVD method (typically, an RF plasma CVD method, a microwave CVD method, an electron cyclotron resonance (ECR) CVD method, or the like), a sputtering method, or the like. With any of the film forming methods, a DLC film can be formed with good adhesion. The DLC film is formed by placing the substrate on the cathode. Alternatively, a dense and hard film can be formed by applying a negative bias and utilizing ion bombardment to some extent.
[0073]
The reaction gas used for the film formation is a hydrogen gas and a hydrocarbon-based gas (eg, CH 2 ₄ , C ₂ H ₂ , C ₆ H ₆ And ionization is performed by glow discharge, and ions are accelerated and collided with a negatively biased cathode to form a film. By doing so, a dense and smooth DLC film can be obtained. The DLC film is an insulating film that is transparent or translucent to visible light.
[0074]
In the present specification, “transparent to visible light” means that the transmittance of visible light is 80 to 100%, and “translucent to visible light” means that the transmittance of visible light is 50 to 80%. Refers to
[0075]
Although not shown here, finally, the substrate is hermetically sealed with a substrate for sealing the EL element, a first sealant surrounding the periphery of the display portion, and a second sealant covering the EL element. A sealing substrate is stuck so as to keep an interval of about 2 to 30 μm, and all the light emitting elements are hermetically sealed. Immediately before the sealing substrate is attached with the second sealing material, it is preferable to perform annealing in a vacuum to perform degassing. It is preferable that all the light-emitting elements be hermetically sealed so as to cover the entire surface with the second sealant and not use a desiccant. Note that when a space is provided between the substrates without using the second sealant and the sealing substrate is attached using only the first sealant, a concave portion is provided in the sealing substrate by a sand blast method or the like. It is preferable that a desiccant is arranged in the concave portion under an atmosphere containing an active gas (a rare gas or nitrogen) and the two are bonded.
[0076]
In addition, although a top gate type TFT has been described as an example here, the present invention can be applied regardless of the TFT structure. For example, the present invention can be applied to a bottom gate type (reverse stagger type) TFT and a forward stagger type TFT. Is possible.
[0077]
(Embodiment 2)
Hereinafter, a method in which a white light-emitting element and a color filter are combined (hereinafter, referred to as a color filter method) will be described with reference to FIG.
[0078]
The color filter method is a method in which a light-emitting element having a layer containing an organic compound that emits white light is formed, and red, green, and blue light is obtained by passing the obtained white light through a color filter.
[0079]
There are various methods for obtaining white light emission. Here, the case of using a light emitting layer made of a polymer material that can be formed by coating will be described. In this case, the doping of the polymer material to be the light emitting layer with the dye can be performed by adjusting the solution, and can be obtained extremely easily as compared with a vapor deposition method in which a plurality of dyes are co-deposited.
[0080]
Specifically, a poly (ethylenedioxythiophene) / poly (styrenesulfone) acting as a hole injection layer is formed on an anode made of a metal (Pt, Cr, W, Ni, Zn, Sn, In) having a large work function. Acid) aqueous solution (PEDOT / PSS) is applied to the entire surface and baked, and then the luminescent center dye (1,1,4,4-tetraphenyl-1,3-butadiene (TPB), 4-dicyanomethylene, which acts as a luminescent layer) After coating and calcining a polyvinyl carbazole (PVK) solution doped with -2-methyl-6- (p-dimethylamino-styryl) -4H-pyran (DCM1), Nile Red, coumarin 6, etc. A thin film containing small metals (Li, Mg, Cs) and a transparent conductive film (ITO (indium oxide tin oxide alloy), indium oxide oxidation) Lead alloy (In ₂ O ₃ (ZnO), zinc oxide (ZnO), etc.). Note that PEDOT / PSS uses water as a solvent and does not dissolve in an organic solvent. Therefore, when PVK is applied from above, there is no need to worry about re-dissolving. Since PEDOT / PSS and PVK have different solvents, it is preferable not to use the same film forming chamber.
[0081]
In the above example, an example in which layers containing an organic compound are stacked is described; however, a layer containing an organic compound may be a single layer. For example, a 1,3,4-oxadiazole derivative (PBD) having an electron transporting property may be dispersed in polyvinyl carbazole (PVK) having a hole transporting property. Further, white light emission can be obtained by dispersing 30 wt% of PBD as an electron transporting agent and dispersing an appropriate amount of four kinds of dyes (TPB, coumarin 6, DCM1, and Nile Red).
[0082]
Note that the layer containing an organic compound is formed between the anode and the cathode, and the holes injected from the anode and the electrons injected from the cathode recombine in the layer containing the organic compound, so that the organic compound is formed. In the containing layer, white light emission is obtained.
[0083]
Alternatively, a layer containing an organic compound emitting red light, a layer containing an organic compound emitting green light, or a layer containing an organic compound emitting blue light can be appropriately selected, and white light emission can be obtained as a whole by overlapping and mixing colors. It is.
[0084]
The layer containing an organic compound formed as described above can obtain white light emission as a whole.
[0085]
The layer containing the organic compound is provided with a colored layer (R) that absorbs light other than red light, a colored layer (G) that absorbs light other than green light, and a colored layer (B) that absorbs light other than blue light in the direction in which white light is emitted. By forming the color filters, white light emission from the light-emitting element can be separated to obtain red light emission, green light emission, and blue light emission. In the case of an active matrix type, a structure is employed in which a TFT is formed between a substrate and a color filter.
[0086]
For the colored layers (R, G, B), a diagonal mosaic arrangement, a triangular mosaic arrangement, an RGBG four-pixel arrangement, an RGBW four-pixel arrangement, or the like can be used, including the simplest stripe pattern.
[0087]
The coloring layer constituting the color filter is formed using a color resist made of an organic photosensitive material in which a pigment is dispersed. The chromaticity coordinates of white light emission are (x, y) = (0.34, 0.35). By combining white light emission and a color filter, color reproducibility as a full color can be sufficiently ensured.
[0088]
Note that, in this case, even if the obtained luminescent colors are different, it is not necessary to separately form the organic compound film for each luminescent color because all of the luminescent colors are formed of organic compound films which emit white light. In addition, a circularly polarizing plate for preventing specular reflection may not be particularly required.
[0089]
Next, a CCM method (color changing media) realized by combining a blue light-emitting element having a layer containing a blue light-emitting organic compound and a fluorescent color conversion layer will be described with reference to FIG.
[0090]
The CCM method excites a fluorescent color conversion layer with blue light emitted from a blue light emitting element, and performs color conversion in each color conversion layer. More specifically, the color conversion layer converts blue to red (B → R), the color conversion layer converts blue to green (B → G), and the color conversion layer converts blue to blue (B → B). ) (The conversion from blue to blue need not be performed) to obtain red, green, and blue light emission. Also in the case of the CCM method, in the case of the active matrix type, a TFT is formed between the substrate and the color conversion layer.
[0091]
Note that also in this case, it is not necessary to separately form layers containing an organic compound. In addition, a circularly polarizing plate for preventing specular reflection may not be particularly required.
[0092]
Further, when the CCM method is used, since the color conversion layer is fluorescent, it is excited by external light, and there is a problem that the contrast is reduced. Therefore, a color filter is attached as shown in FIG. And increase the contrast. At this time, it is not necessary to emit blue light, and for example, white light may be emitted.
[0093]
This embodiment can be combined with Embodiment 1.
[0094]
(Embodiment 3)
Here, another structural example will be described with reference to FIG. Note that FIG. 4 is the same as FIG. 2 except for a part, and thus the same reference numerals are used for the same portions.
[0095]
In FIG. 4, a titanium nitride film 40 is stacked on the titanium film 36a to be thicker than that of FIG. 2, and then a part of the titanium nitride film 40 is formed by etching so as to have a slope. The other structure is the same as that of FIG. 2, and the detailed description is omitted here.
[0096]
This embodiment can be freely combined with Embodiment 1 or 2.
[0097]
The present invention having the above configuration will be described in more detail with reference to the following embodiments.
[0098]
(Example)
[Example 1]
Embodiment 1 In this embodiment, an example of a procedure for forming a light-emitting element of the present invention will be briefly described below with reference to FIGS.
[0099]
First, a base insulating film 31 is formed over a substrate 30 having an insulating surface.
[0100]
The base insulating film 31 is made of SiH ₄ , NH ₃ , And N ₂ A silicon oxynitride film is formed to a thickness of 10 to 200 nm (preferably 50 to 100 nm) using O as a reaction gas. Here, a 50-nm-thick silicon oxynitride film (composition ratio: Si = 32%, O = 27%, N = 24%, H = 17%) is formed. Next, as the second layer of the base insulating film, SiH ₄ And N ₂ A silicon oxynitride film is formed to a thickness of 50 to 200 nm (preferably 100 to 150 nm) using O as a reaction gas. Here, a 100-nm-thick silicon oxynitride film (composition ratio: Si = 32%, O = 59%, N = 7%, H = 2%) is formed. Although a two-layer structure is used as the base insulating film 108 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.
[0101]
Next, a semiconductor layer is formed over the base film. As a semiconductor layer to be an active layer of a TFT, a semiconductor film having an amorphous structure is formed by a known means (a sputtering method, an LPCVD method, a plasma CVD method, or the like) and then a known crystallization treatment (laser crystallization). , A thermal crystallization method, a thermal crystallization method using a catalyst such as nickel, or the like) to form a crystalline semiconductor film obtained by patterning into a desired shape. This semiconductor layer is formed to have a thickness of 25 to 80 nm (preferably 30 to 60 nm). The material of the crystalline semiconductor film is not limited, but is preferably formed using silicon or a silicon-germanium alloy.
[0102]
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, a YVO laser, or the like is used. ₄ Lasers can be used. In the case of using these lasers, a method in which laser light emitted from a laser oscillator is linearly condensed by an optical system and irradiated to a semiconductor film is preferably used. The crystallization conditions are appropriately selected by the practitioner. When an excimer laser is used, the pulse oscillation frequency is 30 Hz, and the laser energy density is 100 to 400 mJ / cm. ² (Typically 200 to 300 mJ / cm ² ). When a YAG laser is used, its second harmonic is used, the pulse oscillation frequency is set to 1 to 10 kHz, and the laser energy density is set to 300 to 600 mJ / cm. ² (Typically 350-500 mJ / cm ² ). Then, a laser beam condensed linearly with a width of 100 to 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 set to 80 to 98%. Good.
[0103]
Next, the surface of the semiconductor layer is washed with an etchant containing hydrofluoric acid to form a gate insulating film 33 covering the semiconductor layer. The gate insulating film 33 is formed of an insulating film containing silicon with a thickness of 40 to 150 nm by a plasma CVD method or a sputtering method. In this embodiment, a silicon oxynitride film (composition ratio: Si = 32%, O = 59%, N = 7%, H = 2%) is formed with a thickness of 115 nm by a plasma CVD method. Needless to say, the gate insulating film 33 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.
[0104]
Next, after cleaning the surface of the gate insulating film 33, a gate electrode is formed.
[0105]
Next, a source region and a drain region 32 are formed by appropriately adding an impurity element (such as B) which imparts p-type to the semiconductor, here, boron. After the addition, heat treatment, intense light irradiation, or laser light irradiation is performed to activate the impurity elements. In addition, plasma damage to the gate insulating film and plasma damage to the interface between the gate insulating film and the semiconductor layer can be recovered simultaneously with the activation. In particular, it is very effective to activate the impurity element by irradiating the second harmonic of the YAG laser from the front surface or the back surface in an atmosphere at room temperature to 300 ° C. The YAG laser is a preferable activation means because of its low maintenance.
[0106]
In the subsequent steps, an interlayer insulating film 35 made of an organic material or an inorganic material (including a coated silicon oxide film, PSG (including phosphorus-added glass, BPSG (boron and phosphorus-added glass)) and the like is formed, and hydrogenation is performed. After that, a contact hole reaching the source region or the drain region is formed, and a source electrode (wiring) 34 and first electrodes (drain electrodes) 36a to 36c are formed to complete a TFT (p-channel TFT). After that, the light absorption multilayer film 38 is formed.
[0107]
In this embodiment, a p-channel TFT has been described. However, it is needless to say that an n-channel TFT can be formed by using an n-type impurity element (P, As, etc.) instead of the p-type impurity element. No.
[0108]
In this embodiment, the top gate type TFT is described as an example. However, the present invention can be applied regardless of the TFT structure. For example, the present invention is applied to a bottom gate type (reverse stagger type) TFT and a forward stagger type TFT. It is possible to
[0109]
Through the above steps, the TFT (the active layer (only the drain region 32 is shown here), the gate insulating film 33, the interlayer insulating film 35, and the first electrodes 36a to 36c) and the light absorbing multilayer film 38 are formed. (FIG. 3 (A))
[0110]
In this embodiment, the first electrodes 36a to 36c are made of Ti, TiN, TiSi _X N _Y , Al, Ag, Ni, W, WSi _X , WN _X , WSi _X N _Y , Ta, TaN _X , TaSi _X N _Y , NbN, Mo, Cr, Pt, Zn, Sn, In, or Mo, or a film mainly composed of an alloy material or a compound material containing the aforementioned element as a main component, or a laminated film of them. The thickness may be in the range of 100 nm to 800 nm.
[0111]
In particular, the first electrode 36a in contact with the drain region 32 is preferably made of a material capable of forming ohmic contact with silicon, typically titanium, and has a thickness of 10 to 100 nm. When the first electrode 36b is formed as a thin film, a material having a large work function (TiN, Pt, Cr, W, Ni, Zn, Sn) is preferable, and the thickness may be in a range of 10 to 100 nm. In particular, when using TiN as an anode, it is desirable to perform ultraviolet irradiation in order to increase the work function. The first electrode 36c is preferably made of a metal material that reflects light, typically a metal material mainly containing Al or Ag, and has a thickness of 100 to 600 nm. Note that the first electrode 36b also functions as a blocking layer that prevents alloying of the first electrode 36c and the first electrode 36a. The light-absorbing multilayer film 38 is preferably formed by stacking a silicon nitride film (thickness: 37 nm), a metal nitride (TiN, TaN, etc.) film (thickness: 66 nm), and a silicon nitride film (thickness: 37 nm). It is preferable that the light-absorbing multilayer film 38 be made of a material that prevents the first electrode 36c from being oxidized, corroded, or prevented from generating hillocks or the like.
[0112]
The first electrodes 36a to 36c can be formed simultaneously with another wiring, for example, the source wiring 34, a power supply line, and the like. Therefore, a process with a small number of photomasks (a patterning mask for a semiconductor layer (first sheet), a patterning mask for gate wiring (second sheet), a doping mask for selectively adding an n-type impurity element (third sheet) ), A doping mask (fourth) for selectively adding a p-type impurity element, a mask (fifth) for forming a contact hole reaching a semiconductor layer in an interlayer film, a first electrode, a source wiring, and a power supply A patterning mask for the supply line (sixth sheet) and a formation mask for the insulator (seventh sheet) (total of seven) can be used. Conventionally, since the first electrode is formed in a layer different from the source wiring and the power supply line, a mask for forming only the first electrode is required, and the total is eight. When the first electrodes 36a to 36c and the wiring are formed at the same time, it is desirable that the total electric resistance of the wiring be low.
[0113]
Next, an insulator (referred to as a bank, a partition, a barrier, a bank, or the like) covering an end portion of the first electrode (and a contact portion with the drain region 32) is formed. (FIG. 3B) Note that a light-absorbing multilayer film 38 is provided at an end of the first electrode, and has a structure in which external light is absorbed. As the insulator 37, an inorganic material (silicon oxide, silicon nitride, silicon oxynitride, or the like), a photosensitive or non-photosensitive organic material (polyimide, acrylic, polyamide, polyimide amide, resist, or benzocyclobutene), or a mixture thereof is used. Although lamination can be used, a photosensitive organic resin is used in this embodiment. For example, when a positive photosensitive acrylic is used as a material of the insulator, it is preferable that only the upper end portion of the insulator have a curved surface having a radius of curvature. Further, as the insulator, either a negative type which becomes insoluble in an etchant by photosensitive light or a positive type which becomes soluble in an etchant by light can be used.
[0114]
Next, as shown in FIG. 3C, the first electrode 36c and the light absorption multilayer film 38 are partially removed while etching the insulator 37. It is important to perform etching so that an inclined surface is formed on the exposed surface of the first electrode 36c and the exposed surface of the first electrode 36b is flat. This etching may be performed once or divided into a plurality of times by dry etching or wet etching, and a condition having a high selectivity between the first electrode 36b and the first electrode 36c is selected. The final radius of curvature of the upper end of the insulator is preferably 0.2 μm to 3 μm. The angle (tilt angle, taper angle) of the inclined surface finally toward the center of the first electrode is more than 30 ° and less than 70 °, preferably 54.7 °, and the organic compound to be formed later is formed. Is reflected from the layer containing.
[0115]
Next, a layer 39 containing an organic compound is formed by an evaporation method or a coating method. (FIG. 2A) For example, when using a vapor deposition method, the degree of vacuum is 5 × 10 ^-3 Torr (0.665 Pa) or less, preferably 10 ^-4 -10 ^-6 Vapor deposition is performed in a film formation chamber evacuated to Pa. At the time of vapor deposition, the organic compound is vaporized by resistance heating in advance, and scatters in the direction of the substrate by opening a shutter during vapor deposition. The vaporized organic compound scatters upward and is deposited on the substrate through an opening provided in the metal mask. By stacking by evaporation, a layer containing an organic compound exhibiting white color is formed as the whole light-emitting element.
[0116]
For example, Alq ₃ , Alq partially doped with a red light-emitting dye Nile Red ₃ , Alq ₃ , P-EtTAZ, and TPD (aromatic diamine) are sequentially laminated to obtain white.
[0117]
In the case where a layer containing an organic compound is formed by a coating method using spin coating, it is preferable to perform baking by vacuum heating after coating. For example, a poly (ethylenedioxythiophene) / poly (styrenesulfonic acid) aqueous solution (PEDOT / PSS) acting as a hole injection layer is applied and baked over the entire surface, and then the luminescent center dye (1, 1) acting as a light emitting layer 1,4,4-tetraphenyl-1,3-butadiene (TPB), 4-dicyanomethylene-2-methyl-6- (p-dimethylamino-styryl) -4H-pyran (DCM1), Nile red, coumarin 6 Etc.) A doped polyvinyl carbazole (PVK) solution may be applied to the entire surface and fired.
[0118]
In the above example, an example in which layers containing an organic compound are stacked is described; however, a layer containing an organic compound may be a single layer. For example, a 1,3,4-oxadiazole derivative (PBD) having an electron transporting property may be dispersed in polyvinyl carbazole (PVK) having a hole transporting property. Further, white light emission can be obtained by dispersing 30 wt% of PBD as an electron transporting agent and dispersing an appropriate amount of four kinds of dyes (TPB, coumarin 6, DCM1, and Nile Red). Further, as a layer containing an organic compound, a layer made of a high molecular material and a layer made of a low molecular material may be stacked.
[0119]
Next, a metal having a small work function (MgAg, MgIn, AlLi, CaF ₂ And a thin film containing an alloy such as CaN or a film formed by co-evaporation of aluminum with an element belonging to Group 1 or 2 of the periodic table and a thin conductive film (here, an aluminum film). Then, the second electrode 40 is obtained. (FIG. 2A) The aluminum film is a film having a high ability to block moisture and oxygen, and is a preferable material for the second electrode 40 in order to improve the reliability of the light emitting device. The second electrode 40 is thin enough to pass light emission, and functions as a cathode in this embodiment. In place of the thin conductive film, a transparent conductive film (ITO (indium tin oxide oxide), indium oxide zinc oxide alloy (In ₂ O ₃ -ZnO), zinc oxide (ZnO) or the like may be used. In order to reduce the resistance of the second electrode 40, an auxiliary electrode that is in contact with the second electrode 40 may be provided. Further, when the second electrode 40 (cathode) is formed, the second electrode 40 may be formed selectively by using a resistance heating method by evaporation and using an evaporation mask.
[0120]
The light-emitting element thus obtained emits white light in the direction of the arrow in FIG. 2A, and can reflect light in the horizontal direction on the inclined surface of the first electrode 36c to increase the amount of light in the direction of the arrow. . In addition, since external light is absorbed by the light-absorbing multilayer film 38 provided on the first electrode 36c, reflected light from the electrodes and the wiring can be suppressed.
[0121]
After the steps up to the formation of the second electrode 40 (conductive film) in the above steps, a sealing substrate (transparent substrate) is attached with a first sealant to seal the light emitting element formed on the substrate 30. . Note that a spacer made of a resin film may be provided in order to secure an interval between the sealing substrate and the light emitting element. The space inside the first sealant is filled with an inert gas such as nitrogen. Note that it is preferable to use an epoxy resin as the first sealant. Further, it is desirable that the first sealant is a material that does not transmit moisture and oxygen as much as possible. Further, a substance (eg, a desiccant) having an effect of absorbing oxygen and water may be contained in the space.
[0122]
By enclosing the light-emitting element in the space as described above, the light-emitting element can be completely shut off from the outside, and a substance which promotes the deterioration of the organic compound layer such as moisture or oxygen from entering from the outside can be prevented. it can. Therefore, a highly reliable light-emitting device can be obtained.
[0123]
[Example 2]
In this embodiment, an example of forming an auxiliary electrode will be described below with reference to FIGS.
[0124]
FIG. 6A is a top view of a pixel, and FIG. 6B is a cross-sectional view taken along a chain line AA ′.
[0125]
In the present embodiment, the steps up to the formation of the insulator 67 are the same as those of the first embodiment, and thus are omitted here. The insulator 37 in FIG. 2B corresponds to the insulator 67 in FIG.
[0126]
According to Embodiment 1, a base insulating film, a drain region 62, a gate insulating film 63, an interlayer insulating film 65, first electrodes 66a to 66, a light absorbing multilayer film 61, and an insulator 67 are formed on a substrate having an insulating surface. .
[0127]
Next, a layer 68 containing an organic compound is selectively formed. In this embodiment, the layer 68 containing an organic compound is selectively formed by an evaporation method using an evaporation mask, an inkjet method, or the like.
[0128]
Next, the auxiliary electrode 60 is selectively formed over the insulator 67 by an evaporation method using an evaporation mask. The thickness of the auxiliary electrode 60 may be set in the range of 0.2 μm to 0.5 μm. In the present embodiment, an example is shown in which the auxiliary electrode 60 is arranged in the Y direction as shown in FIG. 6A, but is not particularly limited, and the auxiliary electrode 70 may be arranged in the X direction as shown in FIG. Good. Note that a cross-sectional view taken along a chain line AA ′ shown in FIG. 7 is the same as FIG. 2A.
[0129]
FIG. 8 shows an external view of a panel corresponding to FIG. The auxiliary electrode (auxiliary wiring) 70 is routed as shown in FIG. 8, and is formed so as to be in contact with the wiring 87 in a region between the pixel portion 82 and the source-side drive circuit 83. In FIG. 8, reference numeral 82 denotes a pixel portion, 83 denotes a source side drive circuit, 84 and 85 denote gate side drive circuits, and 86 denotes a power supply line. The wirings formed at the same time as the first electrode are a power supply line 86, a leading wiring 87, and a source wiring. In FIG. 8, a terminal electrode 88 connected to the FPC is formed at the same time as the gate wiring.
[0130]
Next, as in the first embodiment, a metal having a small work function (MgAg, MgIn, AlLi, CaF ₂ , A thin film including an alloy such as CaN, or a film formed by co-evaporation of aluminum and an element belonging to Group 1 or 2 of the periodic table, and a second electrode 69 (here, a thin aluminum film) on the thin film. Are deposited and laminated. The second electrode 69 is thin enough to pass light emission, and in this embodiment, functions as a cathode. In place of the thin conductive film, a transparent conductive film (ITO (indium tin oxide oxide), indium oxide zinc oxide alloy (In ₂ O ₃ -ZnO), zinc oxide (ZnO) or the like may be used. In this embodiment, in order to reduce the resistance of the second electrode 69, the auxiliary electrode 60 is provided on the insulator 67 so as to be in contact with the second electrode 69.
[0131]
The light-emitting element thus obtained emits white light in the direction of the arrow in FIG. 6B, and can reflect light in the horizontal direction on the inclined surface of the first electrode 66c to increase the amount of light in the direction of the arrow. . Further, external light is absorbed by the light-absorbing multilayer film 61 provided on the first electrode 66c, so that reflected light from the electrodes and the wiring can be suppressed.
[0132]
Further, in the present embodiment, since the resistance of the second electrode 69 is reduced by forming the auxiliary electrodes 60 and 70, the present embodiment can be applied to a pixel having a large size.
[0133]
In this embodiment, the example in which the auxiliary electrode 60 is formed after forming the layer 68 containing an organic compound is described. However, the formation order is not particularly limited. A layer may be formed.
[0134]
This embodiment can be freely combined with any one of Embodiment Modes 1 to 3 and Embodiment 1.
[0135]
[Example 3]
In this embodiment, an external view of the entire active matrix light emitting device will be described with reference to FIG. Note that FIG. 9A is a top view illustrating the light-emitting device, and FIG. 9B is a cross-sectional view of FIG. 9A taken along AA ′. Reference numeral 901 shown by a dotted line denotes a source signal line driving circuit, 902 denotes a pixel portion, and 903 denotes a gate signal line driving circuit. Reference numeral 904 denotes a sealing substrate, 905 denotes a first sealant, and the inside surrounded by the first sealant 905 is a second sealant 907 made of a transparent resin.
[0136]
Note that reference numerals 908 a and 908 b denote wirings for transmitting signals input to the source signal line driver circuit 901 and the gate signal line driver circuit 903. Receive a signal. Although only the FPC is shown here, a printed wiring board (PWB) may be attached to the FPC. The light-emitting device in this specification includes not only the light-emitting device body but also a state in which an FPC or a PWB is attached thereto.
[0137]
Next, a cross-sectional structure is described with reference to FIG. A driver circuit and a pixel portion are formed over a substrate 910; here, a source signal line driver circuit 901 and a pixel portion 902 are illustrated as the driver circuits.
[0138]
Note that as the source signal line driver circuit 901, a CMOS circuit in which an n-channel TFT 923 and a p-channel TFT 924 are combined is formed. Further, the TFT forming the driving circuit may be formed by a known CMOS circuit, PMOS circuit, or NMOS circuit. Further, in this embodiment, a driver integrated type in which a drive circuit is formed on a substrate is shown; however, this is not always necessary, and the driver circuit can be formed outside instead of on the substrate.
[0139]
The pixel portion 902 is formed of a plurality of pixels including a switching TFT 911, a current control TFT 912, and a first electrode 913 (anode) electrically connected to a drain thereof.
[0140]
Insulators 914 are formed at both ends of the first electrode (anode) 913, and a part of the first electrode has a slope along a side surface of the insulator 914. The slope of the first electrode is formed at the same time when the insulator 914 is formed. The light emitted from the layer 915 containing the organic compound is reflected on this slope, so that the amount of light emitted in the light emitting direction indicated by the arrow in FIG. 9 is increased. Further, external light is absorbed by a light-absorbing multilayer film (not shown) provided on the wiring or the electrode, so that reflected light from the electrode or the wiring can be suppressed.
[0141]
Further, a layer 915 containing an organic compound is selectively formed over the first electrode (anode) 913. Further, a second electrode (cathode) 916 is formed over the layer 915 containing an organic compound. Thus, a light-emitting element 918 including the first electrode (anode) 913, the layer 915 containing an organic compound, and the second electrode (cathode) 916 is formed. Here, since the light-emitting element 918 emits white light, a color filter including a colored layer 931 and a BM 932 (an overcoat layer is not illustrated here for simplicity) is provided.
[0142]
An auxiliary electrode 917, which is a part of the structure described in Embodiment 2, is formed over the insulator 914, so that the resistance of the second electrode is reduced. The second electrode (cathode) 916 also functions as a wiring common to all pixels, and is electrically connected to the FPC 909 via the auxiliary electrode 917 and the connection wirings 908a and 908b.
[0143]
In addition, a sealing substrate 904 is attached with a first sealant 905 in order to seal the light-emitting element 918 formed over the substrate 910. Note that a spacer formed of a resin film may be provided in order to secure an interval between the sealing substrate 904 and the light-emitting element 918. The inside of the first sealant 905 is filled with resin (second sealant 907). Note that an epoxy resin is preferably used as the first sealant 905. It is preferable that the first sealant 905 and the second sealant 907 are made of a material that does not transmit moisture and oxygen as much as possible.
[0144]
In this embodiment, a plastic substrate made of FRP (Fiberglass-Reinforced Plastics), PVF (polyvinyl fluoride), mylar, polyester, acrylic, or the like is used as a material of the sealing substrate 904 in addition to a glass substrate or a quartz substrate. be able to. Further, after the sealing substrate 904 is bonded with the sealing agent 905, the sealing substrate 904 can be sealed with a sealing agent so as to further cover the side surface (exposed surface).
[0145]
By enclosing the light-emitting element with the second sealant 907 as described above, the light-emitting element can be completely shut off from the outside, and a substance which promotes the deterioration of the organic compound layer such as moisture or oxygen enters from the outside. Can be prevented. Therefore, a highly reliable light-emitting device can be obtained.
[0146]
This embodiment can be freely combined with Embodiment Modes 1 to 3, Embodiment 1, and Embodiment 2.
[0147]
[Example 4]
By implementing the present invention, all electronic devices incorporating a module having an OLED (active matrix EL module) are completed.
[0148]
Such electronic devices include video cameras, digital cameras, head-mounted displays (goggle-type displays), car navigation systems, projectors, car stereos, personal computers, personal digital assistants (mobile computers, mobile phones, e-books, etc.). No. Examples of these are shown in FIGS.
[0149]
FIG. 10A illustrates a personal computer, which includes a main body 2001, an image input unit 2002, a display unit 2003, a keyboard 2004, and the like.
[0150]
FIG. 10B illustrates a video camera, which includes a main body 2101, a display portion 2102, an audio input portion 2103, operation switches 2104, a battery 2105, an image receiving portion 2106, and the like.
[0151]
FIG. 10C illustrates a mobile computer (mobile computer), which includes a main body 2201, a camera unit 2202, an image receiving unit 2203, operation switches 2204, a display unit 2205, and the like.
[0152]
FIG. 10D illustrates a goggle-type display, which includes a main body 2301, a display portion 2302, an arm portion 2303, and the like.
[0153]
FIG. 10E illustrates a player using a recording medium on which a program is recorded (hereinafter, referred to as a recording medium), and includes a main body 2401, a display portion 2402, a speaker portion 2403, a recording medium 2404, operation switches 2405, and the like. The player can use a DVD (Digital Versatile Disc), a CD, or the like as a recording medium, and can enjoy music, movies, games, and the Internet.
[0154]
FIG. 10F illustrates a digital camera, which includes a main body 2501, a display portion 2502, an eyepiece portion 2503, operation switches 2504, an image receiving portion (not shown), and the like.
[0155]
FIG. 11A illustrates a mobile phone, which includes a main body 2901, an audio output unit 2902, an audio input unit 2903, a display unit 2904, operation switches 2905, an antenna 2906, an image input unit (CCD, image sensor, and the like) 2907, and the like.
[0156]
FIG. 11B illustrates a portable book (e-book) including a main body 3001, display portions 3002 and 3003, a storage medium 3004, operation switches 3005, an antenna 3006, and the like.
[0157]
FIG. 11C illustrates a display, which includes a main body 3101, a support base 3102, a display portion 3103, and the like.
[0158]
Incidentally, the display shown in FIG. 11C is of a small, medium or large size, for example, a screen size of 5 to 20 inches. In addition, in order to form a display portion having such a size, it is preferable to use a substrate having a side of 1 m and mass-produce it by performing multi-paneling. In the case of a small or medium-sized or large-sized one, it is preferable to form the auxiliary electrode shown in the second or third embodiment.
[0159]
As described above, the applicable range of the present invention is extremely wide, and the present invention can be applied to manufacturing methods of electronic devices in all fields. Further, the electronic device of this embodiment can be realized by using any combination of Embodiment Modes 1 to 3 and Embodiments 1 to 3.
[0160]
【The invention's effect】
According to the present invention, light emitted in a lateral direction (a direction parallel to the substrate surface) out of light emitted from a layer containing an organic compound is reflected by a slope formed on a first electrode, and is reflected in a certain direction (a second electrode). In the direction in which light passes through). That is, it is possible to realize a light-emitting device in which light emission loss such as stray light is small.
[0161]
In addition, when the external light is applied, the reflection of the electrodes and the reflection of the wiring other than the light emitting region can be prevented by the provided light absorbing multilayer film.
[0162]
Further, the structure of the present invention can be a manufacturing process in which the total number of masks is small.
[Brief description of the drawings]
FIG. 1 illustrates the first embodiment.
FIG. 2 Simulation results
FIG. 3 is a view showing a first embodiment;
FIG. 4 illustrates a third embodiment.
FIG. 5 illustrates a second embodiment.
FIG. 6 is a diagram showing a second embodiment.
FIG. 7 is a diagram showing a second embodiment.
FIG. 8 is a diagram showing a second embodiment.
FIG. 9 shows a third embodiment.
FIG. 10 illustrates an example of an electronic device.
FIG. 11 illustrates an example of an electronic device.
FIG. 12 is a model diagram used for a simulation.
FIG. 13 is a model diagram used for a simulation.
FIG. 14 is a model diagram used for a simulation.
FIG. 15 is a model diagram used for a simulation.
FIG. 16 is a simulation result of the light absorbing multilayer film of the present invention.
FIG. 17 is a simulation result of the light absorption multilayer film of the present invention.
FIG. 18 is a diagram showing the reflectance of an Al—Ti film and a TiN film.

Claims (27)

A first electrode connected to the thin film transistor over a substrate having an insulating surface;
An insulator covering an end of the first electrode;
A light-emitting element including a layer containing an organic compound in contact with the first electrode and a second electrode in contact with the layer,
The first electrode has an inclined surface toward the center of the first electrode at an end of the first electrode, and the inclined surface reflects light emitted from the layer containing the organic compound;
A light-emitting device, wherein a multilayer film for absorbing external light is provided on an end of the first electrode. A first electrode connected to the thin film transistor over a substrate having an insulating surface;
An insulator covering an end of the first electrode;
A light-emitting element including a layer containing an organic compound in contact with the first electrode and a second electrode in contact with the layer,
The central portion of the first electrode has a concave shape with a smaller thickness than the end portion, and a multilayer film for absorbing external light is provided on the end portion of the first electrode. A light emitting device characterized by the above-mentioned. A first electrode connected to the thin film transistor over a substrate having an insulating surface;
An insulator covering an end of the first electrode;
A light-emitting element including a layer containing an organic compound in contact with the first electrode and a second electrode in contact with the layer,
The first electrode has a multilayer structure, in which the number of layers at the end is larger than the number of layers at the center of the first electrode, and a multilayer film that absorbs external light is provided on the end. A light-emitting device, characterized in that: A first electrode connected to the thin film transistor over a substrate having an insulating surface;
An insulator covering an end of the first electrode;
A light-emitting element including a layer containing an organic compound in contact with the first electrode and a second electrode in contact with the layer,
A light-emitting device, wherein a wiring or an electrode formed on the same layer as the first electrode has a multilayer structure and a multilayer film for absorbing external light is provided. 5. The device according to claim 1, wherein the first electrode has an inclined surface facing a central portion of the first electrode, and an inclination angle is more than 50 ° and less than 60 °. Characteristic light emitting device. In any one of claims 1 to 5, wherein the first multilayer film provided on the end portion of the _{electrode, Al 2 O 3, SiO 2} , ZrO 2, HfO 2, Sc 2 O 3, TiO 2, A light-emitting device comprising at least one layer made of ITO or ZnO. The light-emitting device according to claim 1, wherein the multilayer film provided on an end portion of the first electrode includes at least one light-transmitting nitride insulating film. The multilayer film provided on an end of the first electrode according to any one of claims 1 to 7, wherein the multilayer film is formed of Al, Cu, Au, Mo, Ni, Pt, Rh, Ag, W, Cr, Co, A light emitting device comprising at least one layer made of Si, Zr, Ta, Inconel, or Nichrome. 8. The light-transmitting nitride insulating film, the metal nitride film, and the light-transmitting nitride insulating film according to claim 1, wherein the multilayer film provided on an end portion of the first electrode includes a light-transmitting nitride insulating film, a metal nitride film, and a light-transmitting nitride insulating film. A light-emitting device characterized by being stacked with a film. The light emitting device according to any one of claims 1 to 7, wherein the multilayer film provided on an end portion of the first electrode is a stacked layer of a silicon nitride film, a titanium nitride film, and a silicon nitride film. apparatus. 11. The light-emitting device according to claim 1, wherein the second electrode is a light-transmitting conductive film. 12. The light emitting device according to claim 1, wherein the first electrode has a concave shape, and is formed in a self-aligned manner using the insulator as a mask. 13. The light-emitting device according to claim 1, wherein the first electrode is an anode, and the second electrode is a cathode. 13. The light-emitting device according to claim 1, wherein the first electrode is a cathode, and the second electrode is an anode. The insulator according to any one of claims 1 to 14, wherein the insulator covering an end of the first electrode has a curved surface having a radius of curvature at an upper end, and the radius of curvature is 0.2 μm to 3 μm. A light-emitting device, comprising: 15. The light-emitting device according to claim 1, wherein the layer containing the organic compound is a material that emits red light, a material that emits green light, or a material that emits blue light. The light-emitting device according to claim 1, wherein the layer containing the organic compound is a material that emits white light, and is combined with a color filter provided in a sealing material. The light-emitting device according to any one of claims 1 to 17, wherein the layer containing the organic compound is a material that emits monochromatic light, and is combined with a color conversion layer or a coloring layer provided in a sealing material. 19. The light-emitting device according to claim 1, wherein the light-emitting device is a video camera, a digital camera, a goggle-type display, a car navigation, a personal computer, a DVD player, an electronic game device, or a portable information terminal. Light emitting device. An anode, a layer containing an organic compound in contact with the anode, and a method for manufacturing a light-emitting device including a light-emitting element having a cathode in contact with the layer containing the organic compound,
A step of continuously forming a stack of a metal film and a multilayer film that absorbs light without touching the atmosphere,
Forming an insulator covering an end of the first electrode made of the metal film;
Using the insulator as a mask, performing etching, and thinning the center of the first electrode so that a slope is exposed along the edge of the first electrode;
Forming a film containing an organic compound;
Forming a second electrode made of a light-transmitting metal thin film on the film containing the organic compound. 21. The light-emitting device according to claim 20, wherein the first electrode has a stack of a light-reflective metal film and a metal film serving as an etching stopper, and the light-reflective metal film is etched. A method for manufacturing a light-emitting device, wherein a reflective metal material is exposed. 22. The method for manufacturing a light-emitting device according to claim 20, wherein the first electrode is an anode, and is formed of a metal layer having a larger work function than the second electrode. 23. The first electrode according to claim 20, wherein the first electrode includes a first metal layer including titanium, a second metal layer including titanium nitride or tungsten nitride, and a third metal layer including aluminum. And a method for manufacturing a light-emitting device. 24. The method for manufacturing a light-emitting device according to claim 20, wherein the step of continuously forming a stack of the metal film and the light-absorbing multilayer film is performed by a sputtering method. In any one of claims 20 to 24, multilayer film absorbs the _{light, Al 2 O 3, SiO 2} , ZrO 2, HfO 2, Sc 2 O 3, TiO 2, ITO or a layer composed of ZnO A method for manufacturing a light-emitting device, comprising at least one layer of: The method for manufacturing a light-emitting device according to any one of claims 20 to 25, wherein the light-absorbing multilayer film includes at least one light-transmitting nitride insulating film. The multilayer film for absorbing light according to any one of claims 20 to 26, wherein Ti, Al, Cu, Au, Mo, Ni, Pt, Rh, Ag, W, Cr, Co, Si, Zr, Ta, A method for manufacturing a light-emitting device, comprising at least one layer made of inconel or nichrome.

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