JP3825395B2 - Light emitting device and electric appliance - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a light-emitting device using a light-emitting element in which fluorescence or phosphorescence is obtained by applying an electric field to an element in which a film containing an organic compound (hereinafter referred to as an “organic compound layer”) is provided between a pair of electrodes. . Note that the light-emitting device in this specification refers to an image display device, a light-emitting device, or a light source. Also, modules with light-emitting elements such as connectors such as FPC (Flexible printed circuit) or TAB (Tape Automated Bonding) tape or TCP (Tape Carrier Package), modules with a printed wiring board at the end of TAB tape or TCP In addition, a module in which an IC (integrated circuit) is directly mounted on a light emitting element by a COG (Chip On Glass) method is also included in the light emitting device.
[0002]
[Prior art]
The light emitting element as used in the field of this invention is an element light-emitted by applying an electric field. The light emission mechanism is such that when a voltage is applied with an organic compound layer sandwiched between electrodes, electrons injected from the cathode and holes injected from the anode recombine in the organic compound layer, and excited molecules (Hereinafter referred to as “molecular excitons”), and when the molecular excitons return to the ground state, they are said to emit energy and emit light.
[0003]
In addition, as a kind of molecular exciton which an organic compound forms, it is thought that a singlet excited state and a triplet excited state are possible, However, In this specification, the case where either excited state contributes to light emission is also included. I will do it.
[0004]
In such a light emitting device, the organic compound layer is usually formed as a thin film having a thickness of less than 1 μm. Further, since the light emitting element is a self-luminous element in which the organic compound layer itself emits light, a backlight as used in a conventional liquid crystal display is not necessary. Therefore, it is a great advantage that the light-emitting element can be manufactured to be extremely thin and light.
[0005]
For example, in an organic compound layer of about 100 to 200 nm, the time from carrier injection to recombination is about several tens of nanoseconds considering the carrier mobility of the organic compound layer. Even if the process from light emission to light emission is included, light emission occurs in the order of microseconds or less. Therefore, one of the features is that the response speed is very fast.
[0006]
Due to these characteristics such as thin and light weight, high-speed response, and direct current low voltage drive, the light emitting element is attracting attention as a next-generation flat panel display element. Further, since it is a self-luminous type and has a wide viewing angle, the visibility is relatively good, and it is considered effective as an element used for a display screen of a portable device.
[0007]
In addition, a driving method such as passive matrix driving (simple matrix type) and active matrix driving (active matrix type) can be used for a light-emitting device formed by arranging such light-emitting elements in a matrix. However, when the pixel density increases, the active matrix type in which a switch is provided for each pixel (or one dot) is considered to be advantageous because it can be driven at a lower voltage.
[0008]
As an active matrix light-emitting device, a TFT 1705 and an anode 1702 on a substrate 1701 are electrically connected as shown in FIG. 18, and an organic compound layer 1703 is formed on the anode 1702 to form an organic compound layer. A light emitting element 1707 in which a cathode 1704 is formed over 1703 is provided. Note that as the anode material in the light-emitting element 1707, a conductive material having a large work function is used in order to facilitate hole injection, and ITO (indium tin oxide) or IZO (IZO) is a material that satisfies practical characteristics so far. A conductive material having translucency such as indium zinc oxide) is used. A structure in which light generated in the organic compound layer 1703 of the light-emitting element 1707 is extracted from the light-transmitting anode 1702 toward the TFT 1705 (hereinafter referred to as a bottom emission type) is mainly used.
[0009]
However, in the bottom emission type structure, there is a problem that the aperture ratio is limited due to the arrangement of TFTs, wirings, and the like in the pixel portion even if the resolution is improved.
[0010]
On the other hand, recently, a structure for extracting light from the cathode side (hereinafter referred to as a top emission type) has been devised. In the case of the top emission type, the aperture ratio can be increased as compared with the bottom emission type, and thus it is considered that a light emitting element capable of obtaining higher luminance can be formed (for example, see Patent Document 1). .)
[0011]
[Patent Document 1]
JP 2001-43980 A
[0012]
In the above invention, since there is no light-transmitting material as the cathode material, after forming the cathode, ITO which is a transparent conductive film is laminated, and light is extracted from the cathode side.
[0013]
[Problems to be solved by the invention]
However, in the case of the element structure for extracting light from the cathode side, sufficient film formability is required to maintain the function as the cathode, whereas in order to ensure translucency as the light extraction electrode. In order to satisfy both conditions, a contradiction arises.
[0014]
Therefore, in the present invention, in order to solve these problems, a transparent conductive film such as ITO or IZO, which has already been put into practical use, is used as a light extraction electrode in the production of a top emission type light emitting device. An object of the present invention is to manufacture a light emitting element having a different element structure from that of a conventional top emission type light emitting device.
[0015]
When a transparent electrode is formed as the light extraction electrode, the transparent conductive film is formed after the organic compound layer is formed. Usually, since the transparent conductive film is formed by sputtering, there is a problem that the surface of the organic compound is damaged by sputtering during the film formation, thereby causing element deterioration.
[0016]
Therefore, an object of the present invention is to improve the light emission efficiency of the light emitting element more than before without damaging the organic compound layer in the manufacture of the top emission type light emitting element.
[0017]
[Means for Solving the Problems]
In order to solve the above-described problems, the present invention is characterized in that a protective film is formed at the interface between the anode and the organic compound layer of the light-emitting element including the cathode and the organic compound layer and the anode.
[0018]
Note that in the present invention, the anode is formed of a light-transmitting conductive film and functions as a light extraction electrode. Further, since the cathode is formed on the pixel electrode, the cathode material does not necessarily have light shielding properties, but the laminated film when the pixel electrode and the cathode are laminated needs to have light shielding properties. This is because the light generated in the organic compound layer is efficiently extracted from the anode side. Here, the light shielding property means that the transmittance of visible light to the laminated film is less than 10%. Further, as the cathode material, a material having a work function of 3.8 eV or less is used. By using such a cathode material, the energy barrier between the cathode and the organic compound layer can be relaxed, so that the electron injectability from the cathode is enhanced.
[0019]
A protective film is formed on the organic compound layer formed on the cathode. The protective film referred to in the present specification has a function for preventing sputter damage given to the organic compound layer when forming an anode formed after the organic compound layer is formed. Note that as a material for forming the protective film, a material having a work function of 4.5 to 5.5 eV that can improve the injectability of holes from the anode is used. Furthermore, in the present invention, a mixed region is formed at the interface between the organic compound film and the protective film. Note that a mixed region in this specification refers to a region formed at an interface between an organic compound layer and a protective film and made of a material that forms the organic compound layer and a material that forms the protective film.
[0020]
By forming the mixed region at the interface in this manner, the energy barrier generated by the work function of the material forming the organic compound layer and the work function of the material forming the protective film can be relaxed. The hole transportability can be improved, and the adhesion of the protective film formed on the organic compound layer can be improved, so that the device characteristics can also be improved.
[0021]
Further, after forming the protective film, the anode of the light emitting element is formed. In the present invention, a transparent conductive film such as ITO or IZO, which is a conventional anode material, can be used. It can be produced without change.
[0022]
The configuration of the invention disclosed in the present invention is as follows.
A TFT provided on an insulating surface; an interlayer insulating film formed on the TFT;
A pixel electrode formed on the interlayer insulating film, an insulating film formed to cover an end of the pixel electrode, a cathode formed on the pixel electrode, and an organic compound layer formed on the cathode And a protective film and an anode, wherein the TFT has a source region and a drain region, and the pixel electrode has an opening formed in the interlayer insulating film in the source region or the drain region. Electrically connected to any one of the drain regions, and having a mixed region between the organic compound layer and the protective film, the mixed region comprising the organic compound constituting the organic compound layer, and the protection A light-emitting device including a metal material constituting a film.
[0023]
According to another aspect of the invention, there is provided a TFT provided on an insulating surface, an interlayer insulating film formed on the TFT, a pixel electrode formed on the interlayer insulating film, and an end portion of the pixel electrode A light emitting device comprising: an insulating film formed over the substrate; a cathode formed on the pixel electrode; an organic compound layer formed on the cathode; a protective film; and an anode. A source region and a drain region, and the pixel electrode is electrically connected to either the source region or the drain region at an opening formed in the interlayer insulating film, and the organic compound layer There is a mixed region between the protective film, and the mixed region includes an organic compound that forms the organic compound layer and a metal material that forms the protective film, and an average film thickness thereof is 0.5. -10 nm, preferably A light emitting device which is a 1 to 5 nm.
[0024]
According to another aspect of the present invention, there is provided a TFT provided on an insulating surface, an interlayer insulating film formed on the TFT, a barrier film formed on the interlayer insulating film, and formed on the barrier film. Pixel electrode, an insulating film formed to cover an end of the pixel electrode, a cathode formed on the pixel electrode, an organic compound layer formed on the cathode, a protective film, and an anode The TFT includes a source region and a drain region, and the pixel electrode is connected to the source region or the drain region through an opening formed in an interlayer insulating film and a barrier film. Electrically connected to any one of them, and having a mixed region between the organic compound layer and the protective film, and the mixed region forms the organic compound constituting the organic compound layer and the protective film Including metal materials A light emitting device according to claim.
[0025]
Furthermore, another aspect of the invention includes a TFT provided on an insulating surface, an interlayer insulating film formed on the TFT, a barrier film formed on the interlayer insulating film, and formed on the barrier film. Pixel electrode, an insulating film formed to cover an end of the pixel electrode, a cathode formed on the pixel electrode, an organic compound layer formed on the cathode, a protective film, and an anode The TFT includes a source region and a drain region, and the pixel electrode is connected to the source region or the drain through an opening formed in the interlayer insulating film and the barrier film. Electrically connected to any one of the regions, and having a mixed region between the organic compound layer and the protective film, the mixed region comprising the organic compound constituting the organic compound layer, and the protective film Consists of metal materials It includes and an average thickness thereof is 0.5 to 10 nm, a light-emitting device preferably being a 1 to 5 nm.
[0026]
Note that in the above structure, the barrier film is an insulating material containing aluminum or silicon such as aluminum nitride (AlN), aluminum nitride oxide (AlNO), aluminum oxynitride (AlNO), silicon nitride (SiN), or silicon nitride oxide (SiNO). It consists of a film, and it can prevent degassing such as oxygen from the interlayer insulating film and moisture from entering the light emitting element, and the alkali metal contained as the cathode material can enter the interlayer insulating film side. Can be prevented.
[0027]
Furthermore, another aspect of the invention includes a TFT provided on an insulating surface, an interlayer insulating film formed on the TFT, a pixel electrode formed on the interlayer insulating film, and an end portion of the pixel electrode A light emitting device comprising: an insulating film formed over the substrate; a cathode formed on the pixel electrode; an organic compound layer formed on the cathode; a protective film; and an anode. A source region and a drain region, wherein the pixel electrode is electrically connected to either the source region or the drain region in an opening formed in the interlayer insulating film; The organic compound layer includes a first layer made of an organic compound, and a second layer made of an organic compound different from the substance constituting the first layer. The first layer and the Between the second layer, the organic compound constituting the first layer, and a light-emitting device characterized by having a mixed layer containing an organic compound constituting the second layer.
[0028]
In each of the above structures, the interlayer insulating film and the insulating film are not only insulating films containing silicon such as silicon oxide, silicon nitride, and silicon nitride oxide, but also polyimide, polyamide, acrylic (including photosensitive acrylic), BCB (benzocyclo An organic resin film such as butene can be used. A coated silicon oxide film (SOG: Spin On Glass) formed by a coating method can also be used.
[0029]
In each of the above structures, the pixel electrode functions as a wiring electrically connected to the TFT formed on the substrate, and a low-resistance metal material such as aluminum, titanium, or tungsten is used alone or laminated. It is formed by using.
[0030]
In each of the above configurations, the cathode is made of a material having a small work function and is formed on the pixel electrode. Here, elements belonging to Group 1 or Group 2 of the element periodic rule, that is, alkali metals and alkaline earth metals as well as transition metals containing rare earth metals are suitable. A compound is suitable. This is because a metal having a small work function is unstable in the atmosphere, and oxidation and delamination become a problem.
[0031]
Specifically, cesium fluoride (CsF), calcium fluoride (CaF), barium fluoride (BaF), lithium fluoride (LiF), or the like can be used as the fluoride containing the metal. In addition, an alloy in which silver is added to magnesium (Mg: Ag), an alloy in which lithium is added to aluminum (Al: Li), an alloy containing lithium, calcium, and magnesium in aluminum can be used. Note that an aluminum alloy to which lithium is added can most reduce the work function of aluminum.
[0032]
In addition, although a cathode is formed with the thickness of 1-50 nm using the material mentioned above, when using the fluoride mentioned above, it is preferable to use by 5 nm or less ultrathin film. In addition, materials such as lithium acetylacetonate (Liacac) can be used.
[0033]
In each of the above structures, the organic compound layer is a place where carriers injected from the cathode and the anode are recombined. The organic compound layer may be formed as a single layer consisting of only a light emitting layer, but a plurality of layers such as a hole injection layer, a hole transport layer, a light emitting layer, a blocking layer, an electron transport layer, and an electron injection layer are stacked. The present invention is also included in the present invention. Furthermore, in the case where a plurality of layers are stacked, a layer (this is referred to as a mixed layer in this specification) formed by mixing materials that form adjacent layers is formed at each stack interface. You can also Note that by forming the mixed layer, an energy gap generated at the stack interface can be relaxed, so that carrier mobility in the organic compound layer can be increased and driving voltage can be lowered.
[0034]
In each of the above configurations, the mixed region is composed of a material forming the organic compound layer and a metal material forming the protective film, and the content of the metal material included in the entire mixed region is 10 to 50%. desirable.
[0035]
Furthermore, the organic compound layer in the present invention is not only formed by using a low molecular weight or high molecular weight organic compound, but also an inorganic material (specifically, oxidation of Si and Ge) on a part of the organic compound layer. In addition to the above materials, a material in which any of oxides of carbon nitride (CxNy), alkali metal elements, alkaline earth metal elements, and lanthanoid elements and any of Zn, Sn, V, Ru, Sm, and Ir is combined Etc.) can also be used.
[0036]
In each of the above structures, the protective film is formed on the organic compound layer and has a function of preventing spatter damage during anode formation. Since the protective film is formed in contact with the anode, the material thereof is a metal having a work function (4.5 to 5.5 eV) equal to or higher than that of ITO or the like serving as the anode material. It is formed by using a material. In the present invention, a metal belonging to a transition metal in the element periodic rule can be used. Further, among transition metals, metals such as gold (Au), silver (Ag), and platinum (Pt) belonging to Group 9, 10, or 11 of the periodic table in the long-period type periodic table. Material is preferred.
[0037]
In the case of the element structure of the present invention, since the light generated in the organic compound layer passes through the protective film and is emitted from the anode to the outside, the visible light transmittance needs to be 70 to 100%. is there. Therefore, the transmittance of the anode and the protective film needs to be 70 to 100%. In addition, since the purpose of the protective film in the present invention is to prevent sputter damage at the time of anodic film formation, it is not always necessary to be a uniform film, and it is sufficient if the transmittance can be secured, so that the film thickness is 5 to 50 nm. May be formed.
[0038]
Note that light emission obtained from the light-emitting device of the present invention includes light emission in one or both of the singlet excited state and the triplet excited state.
[0039]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment Modes of the present invention will be described with reference to FIGS. Note that FIG. 1A illustrates an element structure of the light-emitting element 102 formed over the pixel electrode 101.
[0040]
As shown in FIG. 1A, a cathode 103 is formed over the pixel electrode 101, an organic compound layer 104 is formed in contact with the cathode 103, and a protective film 105 is formed in contact with the organic compound layer 104. An anode 106 is formed. Note that electrons are injected from the cathode 103 into the organic compound layer 104, and holes are injected from the anode 106 into the organic compound layer 104. In the organic compound layer 104, light is emitted by recombination of holes and electrons.
[0041]
The pixel electrode 101 has a function of electrically connecting either the source region or the drain region of a thin film transistor (hereinafter referred to as TFT) for driving the light emitting element and the cathode 103. Note that when the pixel electrode 101 is provided separately from the cathode 103 as shown in FIGS. 1A and 1B, the pixel electrode 101 does not directly contact the organic compound layer 104 and functions as an electrode (cathode) of the light-emitting element 102. Therefore, it is only necessary to use a material having high conductivity required for the wiring material. However, when the pixel electrode 101 itself is used as the cathode of the light emitting element, it is necessary to use a metal material having a work function small enough to function as a cathode (specifically, a work function of 3.8 eV or less).
[0042]
Next, a cathode 103 is formed on the pixel electrode 101. Note that a material having a small work function used for the cathode 103 (specifically, a work function of 3.8 eV or less) includes elements belonging to Group 1 or Group 2 of the element periodic rule, that is, alkali metals and alkaline earth metals. In addition, transition metals including rare earth metals are suitable. In the present invention, alloys and compounds containing these are particularly suitable. This is because a metal having a small work function is unstable in the atmosphere, and oxidation and delamination become a problem.
[0043]
The organic compound layer 104 includes a light emitting layer, and includes any one or more of layers having different functions for carriers, such as a hole injection layer, a hole transport layer, a blocking layer, an electron transport layer, and an electron injection layer. It is formed by combining and laminating. Note that a known material can be used as a material for forming the organic compound layer 104. In the present invention, when the organic compound layer has two or more kinds of laminated structures, a layer (hereinafter referred to as a mixed layer) made of a material that forms a layer adjacent to the laminated interface can be formed. Note that by forming a mixed layer at the stack interface, the energy gap can be relaxed by a work function at the interface, so that the transportability of carriers (holes and electrons) inside the organic compound layer can be improved.
[0044]
In the present invention, when the organic compound layer 104 is formed, the mixed region 107 is formed on the organic compound layer 104. Note that the mixed region 107 is formed including the organic compound used to form the organic compound layer 104 and a metal material used to form the protective film 105.
[0045]
Note that the protective film 105 has a function of preventing sputtering damage when the anode 106 is formed. In addition, the formation of a protective film can be expected to prevent moisture, oxygen, and the like from entering the previously formed organic compound layer. Further, since the protective film 105 is formed in contact with the anode 106, the material thereof is the same as or more than that of ITO or the like used as the material of the anode 106 so as not to disturb the hole injection property from the anode. A metal material having a work function (4.5 eV to 5.5 eV) is preferably used.
[0046]
FIG. 1B shows an active matrix type in which a TFT (also referred to as a current control TFT) 111 formed over a substrate 110 and the light-emitting element 102 shown in FIG. The light emitting device is shown.
[0047]
In FIG. 1B, a current control TFT 111 has a source region, a drain region, a channel region, a gate insulating film, and a gate electrode, and an interlayer insulating film 112 is formed so as to cover them. Further, a barrier film 108 is formed to prevent degassing and moisture release from the interlayer insulating film 112, and the pixel electrode 101 is formed simultaneously with the wiring 113 on the barrier film 108.
[0048]
In this embodiment mode, the wiring 113 inputs an electric signal to either the source region or the drain region of the TFT 105, and the pixel electrode outputs an electric signal from the other. 101.
[0049]
Note that an end portion of the pixel electrode 101 is covered with an insulating layer 114, and the cathode 103 is formed on the pixel electrode 101 exposed on the surface. In addition, an organic compound layer 104, a protective film 105, and an anode 106 are stacked over the cathode 103 in a manner similar to that shown in FIG.
[0050]
Here, a method for manufacturing an active matrix light-emitting device will be described with reference to FIGS. 2A to 2D and FIGS. 3A to 3D.
[0051]
In FIG. 2A, a TFT 202 is formed over a substrate 201. Note that although a glass substrate is used as the substrate 201 in this embodiment, a quartz substrate may be used. In the present invention, since light is emitted from the light emitting element to the opposite side of the substrate, the substrate does not have to be particularly light-transmitting, and a known light-shielding material can be used. The TFT 202 may be formed using a known method. The TFT 202 includes at least a gate electrode 203, a source region 205 formed on the opposite side of the gate electrode 203 with the gate insulating film 204 interposed therebetween, a drain region 206, a channel A formation region 207. Note that the channel region 207 is formed between the source region 205 and the drain region 206.
[0052]
Further, as shown in FIG. 2B, an interlayer insulating film 208 is provided with a thickness of 1 to 2 μm so as to cover the TFT 202, and a barrier film 209 is formed over the interlayer insulating film 208.
[0053]
Note that materials for forming the interlayer insulating film 208 include polyimide, polyamide, acrylic (including photosensitive or non-photosensitive acrylic), as well as insulating films containing silicon such as silicon oxide, silicon nitride, and silicon nitride oxide. An organic resin film such as BCB (benzocyclobutene) can be used. Alternatively, a film in which the above-described materials are stacked, such as a stacked film of acrylic and silicon oxide, can be used. Note that the interlayer insulating film is formed by a sputtering method or an evaporation method. Furthermore, a coated silicon oxide film (SOG: Spin On Glass) can also be used as a silicon oxide film formed by a coating method.
[0054]
As a material for forming the barrier film 209, specifically, aluminum nitride (AlN), aluminum nitride oxide (AlNO), aluminum oxynitride (AlON), silicon nitride (SiN), silicon nitride oxide (SiNO), or the like is used. An insulating film containing aluminum or silicon can be used. Moreover, it is desirable to form with the film thickness of 0.2-1.0 micrometer. Note that by providing the barrier film 209, diffusion of alkali metal, water, organic gas, or the like can be prevented.
[0055]
Then, after openings are formed in the interlayer insulating film 208 and the barrier film 209, a conductive film 210 is formed over the barrier film 209 by a sputtering method (FIG. 2C).
[0056]
As a conductive material for forming the conductive film 210, an element selected from tantalum (Ta), tungsten (W), titanium (Ti), molybdenum (Mo), aluminum (Al), and copper (Cu), or the above element is used. An alloy material or a compound material as a main component can be used. Moreover, it is good also as a laminated structure combining these two or more. Note that a three-layer structure in which a 50 nm-thickness tungsten film, a 500 nm-thickness aluminum-silicon alloy (Al—Si) film, and a 30 nm-thickness titanium nitride film are sequentially stacked is used here.
[0057]
Next, as shown in FIG. 2D, the conductive film 210 is patterned to form a wiring 211 electrically connected to the TFT 202. In the present invention, the pixel electrode 212 that also functions as a wiring is formed at the same time. As a patterning method, either a dry etching method or a wet etching method may be used.
[0058]
Further, as shown in FIG. 3A, an insulating layer 213 is formed so as to cover the gap between the end of the anode and the anode. Note that the insulating layer 213 can be obtained by forming an opening over the pixel electrode after forming the insulating film. As a material for forming the insulating layer 213, in addition to a material containing silicon such as silicon oxide, silicon nitride, and silicon nitride oxide, an organic resin such as polyimide, polyamide, acrylic (including photosensitive acrylic), and BCB (benzocyclobutene) is used. A membrane can be used. Furthermore, a coated silicon oxide film (SOG: Spin On Glass) can also be used as the silicon oxide film. The film thickness can be 0.1 to 2 μm. In particular, when a material containing silicon such as silicon oxide, silicon nitride, and silicon nitride oxide is used, the film thickness is 0.1 to 0.3 μm. It is desirable to form with.
[0059]
Next, the cathode 214 is formed. Note that the cathode 214 is manufactured by patterning a cathode material using a metal mask by a sputtering method or a vapor deposition method. Note that a material for forming the cathode 214 is preferably a material having a low work function in order to improve electron injectability from the cathode 214, and elements belonging to Group 1 or Group 2 of the element periodic rule, that is, alkali metals and alkaline earths. In addition to similar metals, transition metals including rare earth metals can be used.
[0060]
Specifically, cesium fluoride (CsF), calcium fluoride (CaF), barium fluoride (BaF), lithium fluoride (LiF), or the like can be used as the fluoride containing the metal. In addition, an alloy in which silver is added to magnesium (Mg: Ag), an alloy in which lithium is added to aluminum (Al: Li), an alloy containing lithium, calcium, and magnesium in aluminum can be used. Note that an aluminum alloy to which lithium is added can most reduce the work function of aluminum.
[0061]
In addition, although the cathode 214 is formed with the thickness of 1-50 nm using the material mentioned above, when using the fluoride mentioned above, it is preferable to use it with an ultra-thin film of 5 nm or less. In addition, materials such as lithium acetylacetonate (Liacac) can be used.
[0062]
Next, an organic compound layer 215 is formed over the cathode 214 (FIG. 3B). Note that as a material for forming the organic compound layer 215, a known organic compound of low molecular weight, high molecular weight, or medium molecular weight can be used. The term “medium molecular organic compound” as used herein refers to an aggregate (preferably having a molecule number of 10 or less) of organic compounds having no sublimation property or solubility, or a chain molecule length of 5 μm or less (preferably Organic compound of 50 nm or less). As a film formation method, an evaporation method (resistance heating method), a spin coating method, an ink jet method, a printing method, or the like can be used. Note that the organic compound layer can be patterned by forming a film using a metal mask.
[0063]
In addition, even if the organic compound layer 215 has either a single layer structure or a stacked structure, the film thickness is desirably 10 to 300 nm.
[0064]
Next, a mixed region 216 is formed on the organic compound layer 215. The mixed region 216 is formed by using the organic compound used for forming the organic compound layer 215 (the organic compound forming the outermost layer when the organic compound layer has a laminated structure), and the following: The material for forming the protective film 217 (metal material) is used.
[0065]
For example, when the organic compound layer 215 is formed by a vapor deposition method, it is formed by co-evaporation with a metal material, and when the organic compound layer 215 is formed by a coating method such as a spin coating method, It is formed by applying a mixed liquid in which a metal material is mixed.
[0066]
Note that in the case where the mixed region 216 is formed by vapor deposition, film formation is performed in a vapor deposition chamber as shown in FIG. As shown in FIG. 17, the substrate 301 is fixed to a holder 302, and an evaporation source 303 is provided below the substrate 301. The evaporation source 303a includes an organic compound 304a, and the evaporation source 303b includes a metal material 304b. Further, a shutter 306 (306a, 306b) is formed in each of the evaporation sources 303 (303a, 303b). Note that the evaporation source 303 (303a and 303b) or the substrate to be deposited is preferably moved (rotated) so that the film is uniformly formed in the film formation chamber. Note that only two evaporation sources are shown here, but when an organic compound layer has a laminated structure, a plurality of organic compounds are required. Can do.
[0067]
The evaporation source 303 (303a, 303b) is made of a conductive material. When the internal organic compound 304a or the metal material 304b is heated by a resistance generated when a voltage is applied thereto, the evaporation source 303 (303a, 303b) is vaporized. It is deposited on the surface of the substrate 301. In this specification, the surface of the substrate 301 includes a substrate and a thin film formed thereon. Here, a TFT, a pixel electrode connected to the TFT, and a cathode are formed on the substrate 301. Yes.
[0068]
Note that the shutter 306 (306a, 306b) controls vapor deposition of the vaporized organic compound 304a or the metal material 304b. That is, when the shutter is open, the organic compound 304a or the metal material 304b evaporated by heating can be deposited.
[0069]
Further, the deposition chamber is provided with an adhesion shield 307, and an organic compound that has not been deposited on the substrate during deposition can be attached. Since the entire deposition shield 307 can be heated by the heating wire 308 provided around the deposition shield 307, the deposited organic compound can be vaporized, so that the organic compound that has not been deposited is recovered again. can do.
[0070]
For example, the organic compound layer 215 described above is formed by vapor-depositing the organic compound provided in the first evaporation source 303a, and the second evaporation source 303b is provided with a metal material that forms the protective film 217. Suppose that In this case, the mixed region 216 is formed by simultaneously vapor-depositing (co-evaporating) the organic compound provided in the first evaporation source 303a and the metal material provided in the second evaporation source 303b on the substrate. can do. Note that the mixed region 216 formed in this embodiment is formed so that the average film thickness is 0.5 to 10 nm, and preferably 1 to 5 nm.
[0071]
Note that after forming the mixed region 216, only the shutter 306a of the first evaporation source 303a is closed, thereby forming a protective film 217 made of only a metal material from the second evaporation source 303b on the mixed region 216. (FIG. 3B). Note that the impurity contamination at the interface can be prevented by continuously performing the film formation here.
[0072]
Note that a metal material for forming the protective film 217 is a metal having a work function (specifically, 4.5 to 5.5 eV) equal to or higher than that of ITO or the like used as the material of the anode 217. It is formed by using a material. For example, using a metal material belonging to Group 9, Group 10 or Group 11 in the long-period element periodic table such as gold (Au), platinum (Pt), palladium (Pd), nickel (Ni), etc. Can be formed. In addition, the protective film in the present invention is not necessarily a uniform film because the purpose is to prevent sputtering damage to the organic compound layer when the anode 217 is formed. Therefore, it is preferable to use a conductive film having a visible light transmittance of 70 to 100% and a thickness of 0.5 to 5 nm.
[0073]
Further, the anode 218 is formed over the protective film 217, whereby the light emitting element 219 is completed. As a material for forming the anode 218, in addition to ITO and IZO, IDIXO (In ₂ O _Three A transparent conductive film such as -ZnO) is used and formed by a sputtering method.
[0074]
Although the top gate type TFT has been described as an example here, the present invention is not particularly limited, and can be applied to a bottom gate type TFT, a forward stagger type TFT, and other TFT structures instead of the top gate type TFT. It is.
[0075]
With such a structure, in the organic compound layer 215, light emission generated by carrier recombination can be efficiently emitted from the anode 218 side.
[0076]
In the light emitting device of the present invention, the structure shown in FIGS. 4A and 4B can be used. The structure shown in FIG. 4A is different from the structure shown in FIG. 1A in that ITO is used as a material for forming the pixel electrode 401, and the cathode material. The description in A) and (B) may be referred to.
[0077]
Further, FIG. 4B illustrates an active matrix type in which a TFT (also referred to as a current control TFT) 411 formed over the substrate 410 and the light-emitting element 402 illustrated in FIG. 4A are electrically connected. 1 has a structure different from that shown in FIG. 1B in that the wiring 413 and the pixel electrode 401 are formed separately and the pixel electrode is formed of ITO. In the case of forming this structure, it is desirable to form the cathode 403 so as to have a light shielding property in order to prevent useless light emission from the pixel electrode side. As in FIGS. 1A and 1B, the cathode material is a material having a small work function (specifically, the work function is 3.8 eV or less), and the film thickness is increased. Therefore, it is desirable to use a material that can have light shielding properties.
[0078]
The light emitting device of the present invention having the above structure will be described in more detail with reference to the following examples.
[0079]
【Example】
Examples of the present invention will be described below.
[0080]
Example 1
In this example, an element structure of a light-emitting element included in the light-emitting device of the present invention will be described in detail with reference to FIGS. In particular, the case where the organic compound layer is formed using a low molecular weight compound will be described.
[0081]
As described in the embodiment, the cathode 501 is formed over the pixel electrode. In this embodiment, the cathode 501 is formed with a film thickness of 5 nm by vapor deposition using CsF.
[0082]
Then, an organic compound layer 503 is formed on the cathode 501, but first, an electron transport layer 504 is formed. The electron transport layer 504 is formed using an electron transport material having electron acceptability. In this embodiment, tris (8-quinolinolato) aluminum (hereinafter referred to as Alq) is used as the electron transport layer 504. _Three Is formed by a vapor deposition method with a film thickness of 40 nm.
[0083]
Further, a blocking layer 505 is formed. The blocking layer 505 is also referred to as a hole blocking layer. When holes injected into the light emitting layer 506 pass through the electron transport layer 504 and reach the cathode 501, a wasteful current that does not participate in recombination flows. It is a layer to prevent In this embodiment, bathocuproine (hereinafter referred to as BCP) is formed as the blocking layer 505 by a vapor deposition method with a thickness of 10 nm.
[0084]
Next, the light emitting layer 506 is formed. In this embodiment, holes and electrons are recombined in the light emitting layer 506 to emit light. Note that the light-emitting layer 506 uses 4,4′-dicarbazole-biphenyl (hereinafter, referred to as CBP) as a hole-transporting host material, and tris (2-phenylpyridine) iridium (a light-emitting organic compound). Ir (ppy) _Three ) To form a film with a thickness of 30 nm.
[0085]
Next, the hole transport layer 507 is formed of a material having excellent hole transportability. Here, 4,4′-bis [N- (1-naphthyl) -N-phenyl-amino] -biphenyl (hereinafter referred to as α-NPD) is formed to a thickness of 40 nm by an evaporation method.
[0086]
Finally, the hole injection layer 508 is formed, whereby the organic compound layer 503 having a stacked structure is completed. Note that the hole-injection layer 508 has a function of improving the hole-injection property from the anode. In this embodiment, as the hole injection layer 508, copper phthalocyanine (Cu—Pc) is formed to a thickness of 30 nm. Note that a vapor deposition method is used.
[0087]
Next, the mixed region 511 is formed by co-evaporating the material used for forming the hole injection layer 508 and the material of the protective film to be formed later. In this embodiment, Cu—Pc and gold are co-evaporated to form a film with a thickness of 1 to 2 nm.
[0088]
After forming the mixed region 511, a protective film 509 is formed. Note that as the metal material for forming the protective film 509, specifically, a conductive film having a visible light transmittance of 70 to 100% and a work function of 4.5 to 5.5 is used. Further, since the metal film is often opaque to visible light, it is formed with a thickness of 0.5 to 5 nm. In this embodiment, as described above, gold is used and a film thickness of 4 nm is formed by vapor deposition.
[0089]
Next, the anode 510 is formed. In the present invention, since the anode 510 is an electrode that transmits light generated in the organic compound layer 503, the anode 510 is formed using a light-transmitting material. In addition, since the anode 510 is an electrode for injecting holes into the organic compound layer 503, the anode 510 needs to be formed of a material having a high work function. In this embodiment, as a material for forming the anode 510, an indium tin oxide (ITO) film or a transparent conductive film in which 2 to 20% zinc oxide (ZnO) is mixed with indium oxide is formed by sputtering to 100 nm. The film is used to have a film thickness of Note that the anode 510 can be formed using another known material (IZO, IDIXO, or the like) as long as it is a transparent conductive film having a high work function.
[0090]
In this embodiment, as shown in FIG. 5B, the stacked interface of the electron transport layer 504, the blocking layer 505, the light emitting layer 506, the hole transport layer 507, and the hole injection layer 508 forming the organic compound layer 503 is formed. It is also possible to form a mixed layer made of a material that forms a layer adjacent to each other.
[0091]
Specifically, the mixed layer I (531) is formed at the stacked interface between the electron transport layer 504 and the blocking layer 505, and the mixed layer II (532) is formed at the stacked interface between the blocking layer 505 and the light emitting layer 506. A mixed layer III (533) is formed at the stacked interface between the light emitting layer 506 and the hole transport layer 507, and a mixed layer IV (534) is formed at the stacked interface between the hole transport layer 507 and the hole injection layer 508. In this embodiment, the mixed layer I (531) is made of Alq. _Three And BCP are co-evaporated to form mixed layer II (532) with BCP, CBP, and (Ir (ppy) _Three ) Are co-evaporated, and the mixed layer III (533) is converted into CBP, (Ir (ppy) _Three ), And α-NPD are co-evaporated, and the mixed layer IV (534) is co-evaporated with α-NPD and Cu—Pc.
[0092]
Note that FIG. 5B is a preferable example, and thus it is not always necessary to form a mixed layer at the entire stack interface of the organic compound layer. For example, the blocking layer 505 in contact with the light-emitting layer 506, and A mixed layer may be formed only at the interface with the hole transport layer 507.
[0093]
Through the above steps, a light-emitting element formed using a low molecular material for the organic compound layer can be formed.
[0094]
(Example 2)
In this example, an element structure of a light-emitting element included in the light-emitting device of the present invention will be described in detail with reference to FIGS. 6 (A) to (C). In particular, an element structure formed using a polymer compound in the organic compound layer will be described.
[0095]
As described in the embodiment, the cathode 701 is formed over the pixel electrode. In this embodiment, the cathode 701 is formed with a film thickness of 5 nm by vapor deposition using CaF.
[0096]
In this embodiment, the organic compound layer 702 formed on the cathode 701 has a stacked structure of a light emitting layer 703 and a hole transport layer 704. Note that the organic compound layer 702 in this embodiment is formed using a high molecular organic compound.
[0097]
The light-emitting layer 703 can be formed using a polyparaphenylene vinylene-based material, a polyparaphenylene-based material, a polythiophene-based material, or a polyfluorene-based material.
[0098]
Examples of the polyparaphenylene vinylene-based material include poly (p-phenylene vinylene) (hereinafter referred to as PPV) and poly (2- (2′-ethyl-hexoxy)) that can emit orange light. -5-methoxy-1,4-phenylene vinylene) (poly [2- (2'-ethylhexoxy) -5-methoxy-1,4-phenylene vinylene]) (hereinafter referred to as MEH-PPV), green light emission The resulting poly (2- (dialkoxyphenyl) -1,4-phenylene vinylene) (poly [2- (dialkoxyphenyl) -1,4-phenylene vinylene]) (hereinafter referred to as ROPh-PPV) or the like can be used. it can.
[0099]
As a polyparaphenylene-based material, poly (2,5-dialkoxy-1,4-phenylene) (hereinafter referred to as RO— Poly (2,5-dihexoxy-1,4-phenylene)) or the like can be used.
[0100]
Examples of polythiophene-based materials include poly (3-alkylthiophene) (hereinafter referred to as PAT), poly (3-hexylthiophene) (poly (3-hexylthiophene) (poly (3-hexylthiophene)). )) (Hereinafter referred to as PHT), poly (3-cyclohexylthiophene) (hereinafter referred to as PCHT), poly (3-cyclohexyl-4-methylthiophene) (poly (3-cyclohexyl) -4-methylthiophene)) (hereinafter referred to as PCHMT), poly (3,4-dicyclohexylthiophene) (hereinafter referred to as PDCHT), poly [3- (4-octylphenyl) ) -Thiophene] (poly [3- (4octylphenyl) -thiophene]) (hereinafter referred to as POPT), poly [3- (4-octylphenyl) -2,2-bithiophene] (poly [3- (4-octylphenyl)) -2,2-bithiophene]) (hereinafter PTOP) And the like can be used.
[0101]
Furthermore, poly (9,9-dialkylfluorene) (hereinafter referred to as PDAF), poly (9,9-dioctylfluorene), which can obtain blue light emission, is a polyfluorene-based material. (poly (9,9-dioctylfluorene) (hereinafter referred to as PDOF) or the like can be used.
[0102]
These materials are formed by applying a solution dissolved in an organic solvent by a coating method. In addition, as an organic solvent used here, toluene, benzene, chlorobenzene, dichlorobenzene, chloroform, tetralin, xylene, dichloromethane, cyclohexane, NMP (N-methyl-2-pyrrolidone), dimethyl sulfoxide, cyclohexanone, dioxane, THF (tetrahydrofuran) ) Etc.
[0103]
In this embodiment, a film made of PPV is formed as the light emitting layer 703 with a thickness of 80 nm.
[0104]
The hole transport layer 704 is formed by using both PEDOT (poly (3,4-ethylene dioxythiophene)) and polystyrene sulfonic acid (hereinafter referred to as PSS) which is an acceptor material, as well as polyaniline (hereinafter referred to as PANI). ) And camphor sulfonic acid (hereinafter referred to as CSA) which is an acceptor material. Since these materials are water-soluble, an aqueous solution is applied by a coating method to form a film. In this embodiment, a film made of PEDOT and PSS is formed with a thickness of 30 nm as the hole transport layer 704. Through the above, an organic compound layer 702 in which the light-emitting layer 703 and the hole transport layer 704 are stacked can be obtained.
[0105]
Next, a mixed region 707 is formed by applying a mixture of a protective film material to be formed later to the coating liquid used to form the hole transport layer 704. In this embodiment, a coating solution in which gold is mixed with an aqueous solution containing PEDOT and a PSS material is applied to form a film with a thickness of 1 to 2 nm.
[0106]
After forming the mixed region 707, a protection 705 is formed. Note that as the metal material for forming the protective film 705, specifically, a conductive film having a visible light transmittance of 70 to 100% and a work function of 4.5 to 5.5 is used. Further, since the metal film is often opaque to visible light, it is formed with a thickness of 0.5 to 5 nm. Note that in this embodiment, gold is used and a film thickness of 4 nm is formed by an evaporation method.
[0107]
Next, an anode 706 is formed. In the present invention, since the anode 706 is an electrode that transmits light generated in the organic compound layer 702, the anode 706 is formed using a light-transmitting material. Further, since the anode 706 is an electrode for injecting holes into the organic compound layer 702, it needs to be formed of a material having a high work function. In this embodiment, as a material for forming the anode 706, an indium tin oxide (ITO) film or a transparent conductive film in which 2 to 20% zinc oxide (ZnO) is mixed with indium oxide is formed by sputtering to 100 nm. The film is used to have a film thickness of Note that the anode 706 can also be formed using another known material (IZO, IDIXO, or the like) as long as it is a transparent conductive film having a high work function.
[0108]
In this embodiment, as shown in FIG. 6B, a mixed layer 731 made of a material that forms a layer adjacent to the stacked interface between the light-emitting layer 703 and the hole-transport layer 704 that form the organic compound layer 702 is formed. It can also be formed.
[0109]
Through the above, a light-emitting element formed using a polymer material for the organic compound layer can be formed.
[0110]
Example 3
An embodiment of the present invention will be described with reference to FIGS. Here, a method for simultaneously manufacturing a pixel portion and TFTs (n-channel TFT and p-channel TFT) of a driver circuit provided around the pixel portion on the same substrate will be described in detail.
[0111]
First, a base insulating film 601 is formed over a substrate 600, a first semiconductor film having a crystal structure is obtained, and then a semiconductor layer 602 to 605 separated into island shapes is formed by etching treatment into a desired shape. .
[0112]
As the substrate 600, a glass substrate (# 1737) is used, and as the base insulating film 601, a film forming temperature of 400 ° C. by a plasma CVD method and a source gas SiH _Four , NH _Three , N ₂ A silicon oxynitride film 601a (composition ratio Si = 32%, O = 27%, N = 24%, H = 17%) formed from O is formed to a thickness of 50 nm (preferably 10 to 200 nm). Next, after cleaning the surface with ozone water, the oxide film on the surface is removed with dilute hydrofluoric acid (1/100 dilution). Next, the film formation temperature is 400 ° C. by the plasma CVD method, and the source gas SiH. _Four , N ₂ A silicon oxynitride film 601b (composition ratio Si = 32%, O = 59%, N = 7%, H = 2%) formed from O is stacked to a thickness of 100 nm (preferably 50 to 200 nm), Furthermore, the film deposition temperature is 300 ° C. and the film deposition gas SiH is formed by plasma CVD without opening to the atmosphere. _Four A semiconductor film having an amorphous structure (here, an amorphous silicon film) is formed with a thickness of 54 nm (preferably 25 to 80 nm).
[0113]
Although the base film 601 is shown as a two-layer structure in this embodiment, it may be formed as a single-layer film of the insulating film or a structure in which two or more layers are stacked. The material of the semiconductor film is not limited, but preferably silicon or silicon germanium (Si _1-X Ge _X (X = 0.0001 to 0.02)) An alloy or the like may be used and may be formed by a known means (such as sputtering, LPCVD, or plasma CVD). The plasma CVD apparatus may be a single wafer type apparatus or a batch type apparatus. Alternatively, the base insulating film and the semiconductor film may be successively formed without being exposed to the air in the same film formation chamber.
[0114]
Next, after cleaning the surface of the semiconductor film having an amorphous structure, an extremely thin oxide film of about 2 nm is formed on the surface with ozone water. Next, a small amount of impurity element (boron or phosphorus) is doped in order to control the threshold value of the TFT. Here, diborane (B ₂ H ₆ ) Using a plasma-excited ion doping method without mass separation, a doping condition of an acceleration voltage of 15 kV, diborane diluted to 1% with hydrogen, a gas flow rate of 30 sccm, a dose of 2 × 10 ¹² / Cm ² Then, boron was added to the amorphous silicon film.
[0115]
Next, a nickel acetate salt solution containing 10 ppm of nickel in terms of weight is applied with a spinner. Instead of coating, a method of spreading nickel element over the entire surface by sputtering may be used.
[0116]
Next, heat treatment is performed for crystallization, so that a semiconductor film having a crystal structure is formed. For this heat treatment, heat treatment in an electric furnace or irradiation with strong light may be used. When the heat treatment is performed in an electric furnace, the heat treatment may be performed at 500 to 650 ° C. for 4 to 24 hours. Here, after heat treatment for dehydrogenation (500 ° C., 1 hour), heat treatment for crystallization (550 ° C., 4 hours) is performed to obtain a silicon film having a crystal structure. Although crystallization is performed here using heat treatment using a furnace, crystallization may be performed using a lamp annealing apparatus capable of crystallization in a short time. Although a crystallization technique using nickel as a metal element for promoting crystallization of silicon is used here, other known crystallization techniques such as a solid phase growth method and a laser crystallization method may be used.
[0117]
Next, after removing the oxide film on the surface of the silicon film having a crystal structure with dilute hydrofluoric acid or the like, irradiation with laser light (XeCl: wavelength 308 nm) for increasing the crystallization rate and repairing defects left in the crystal grains In the air or in an oxygen atmosphere. For laser light, excimer laser light with a wavelength of 400 nm or less, YVO _Four The second and third harmonics of the laser are used. In any case, pulse laser light having a repetition frequency of about 10 to 1000 Hz is used, and the laser light is 100 to 500 mJ / cm in the optical system. ² And the surface of the silicon film may be scanned by irradiating with a 90 to 95% overlap rate. Here, a repetition frequency of 30 Hz and an energy density of 393 mJ / cm ² Irradiate laser light in the atmosphere. Note that since the reaction is performed in the air or in an oxygen atmosphere, an oxide film is formed on the surface by laser light irradiation.
[0118]
Alternatively, after removing the oxide film formed by laser light irradiation with dilute hydrofluoric acid, the surface of the semiconductor film may be planarized by performing second laser light irradiation in a nitrogen atmosphere or in a vacuum. In this case, excimer laser light having a wavelength of 400 nm or less, second harmonic and third harmonic of a YAG laser are used as this laser light (second laser light). The energy density of the second laser light is larger than the energy density of the first laser light, preferably 30 to 60 mJ / cm. ² Enlarge.
[0119]
Note that the laser light irradiation here has a gettering effect also in preventing the addition of a rare gas element to the silicon film having a crystal structure when an oxide film is formed and then formed by sputtering. It is very important to increase. Next, in addition to the oxide film formed by laser light irradiation, the surface is treated with ozone water for 120 seconds to form a barrier layer made of an oxide film having a total thickness of 1 to 5 nm.
[0120]
Next, an amorphous silicon film containing an argon element serving as a gettering site is formed with a thickness of 150 nm on the barrier layer by a sputtering method. The film formation conditions by the sputtering method of this embodiment are as follows: the film formation pressure is 0.3 Pa, the gas (Ar) flow rate is 50 (sccm), the film formation power is 3 kW, and the substrate temperature is 150 ° C. Note that the atomic concentration of the argon element contained in the amorphous silicon film under the above conditions is 3 × 10 ²⁰ / Cm ^Three ~ 6 × 10 ²⁰ / Cm ^Three The atomic concentration of oxygen is 1 × 10 ¹⁹ / Cm ^Three ~ 3x10 ¹⁹ / Cm ^Three It is. Thereafter, heat treatment is performed at 650 ° C. for 3 minutes using a lamp annealing apparatus to perform gettering.
[0121]
Next, the amorphous silicon film containing an argon element as a gettering site is selectively removed using the barrier layer as an etching stopper, and then the barrier layer is selectively removed with dilute hydrofluoric acid. Note that during gettering, nickel tends to move to a region with a high oxygen concentration, and thus it is desirable to remove the barrier layer made of an oxide film after gettering.
[0122]
Next, after forming a thin oxide film with ozone water on the surface of the obtained silicon film having a crystal structure (also called a polysilicon film), a mask made of resist is formed and etched into a desired shape to form an island shape. A separated semiconductor layer is formed. After the semiconductor layer is formed, the resist mask is removed.
[0123]
Further, after forming the semiconductor layer, an impurity element imparting p-type or n-type conductivity may be added in order to control the threshold value (Vth) of the TFT. As impurity elements imparting p-type to a semiconductor, periodic group 13 elements such as boron (B), aluminum (Al), and gallium (Ga) are known. Note that as an impurity element imparting n-type conductivity to a semiconductor, an element belonging to Group 15 of the periodic table, typically phosphorus (P) or arsenic (As) is known.
[0124]
Next, after forming a thin oxide film with ozone water on the surface of the obtained silicon film having a crystal structure (also called a polysilicon film), a mask made of resist is formed and etched into a desired shape to form islands. The separated semiconductor layers 602 to 605 are formed. After the semiconductor layer is formed, the resist mask is removed.
[0125]
Next, the oxide film is removed with an etchant containing hydrofluoric acid, and at the same time, the surface of the silicon film is washed, and then an insulating film containing silicon as a main component to be the gate insulating film 607 is formed. Note that as the gate insulating film 607, a laminated film formed of a silicon oxide film and a silicon nitride film formed by a sputtering method using Si as a target, a silicon oxynitride film formed by a plasma CVD method, or a silicon oxide film Can be used. In this embodiment, a silicon oxynitride film (composition ratio: Si = 32%, O = 59%, N = 7%, H = 2%) is formed to a thickness of 115 nm by plasma CVD.
[0126]
Next, as illustrated in FIG. 7A, a first conductive film 608 with a thickness of 20 to 100 nm and a second conductive film 609 with a thickness of 100 to 400 nm are stacked over the gate insulating film 607. In this embodiment, a tantalum nitride film having a thickness of 50 nm and a tungsten film having a thickness of 370 nm are sequentially stacked over the gate insulating film 607.
[0127]
The conductive material for forming the first conductive film and the second conductive film is an element selected from Ta, W, Ti, Mo, Al, and Cu, or an alloy material or a compound material containing the element as a main component. Form. Alternatively, a semiconductor film typified by a polycrystalline silicon film doped with an impurity element such as phosphorus, or an Ag: Pd: Cu alloy may be used as the first conductive film and the second conductive film. Further, the present invention is not limited to the two-layer structure. For example, a three-layer structure in which a 50 nm-thickness tungsten film, a 500 nm-thickness aluminum and silicon alloy (Al-Si) film, and a 30 nm-thickness titanium nitride film are sequentially stacked. Also good. In the case of a three-layer structure, tungsten nitride may be used instead of tungsten of the first conductive film, or aluminum instead of the aluminum and silicon alloy (Al-Si) film of the second conductive film. A titanium alloy film (Al—Ti) may be used, or a titanium film may be used in place of the titanium nitride film of the third conductive film. Moreover, a single layer structure may be sufficient.
[0128]
Next, as shown in FIG. 7B, resist masks 610 to 613 are formed by a light exposure process, and a first etching process is performed to form gate electrodes and wirings. The first etching process is performed under the first and second etching conditions. For etching, an ICP (Inductively Coupled Plasma) etching method may be used. Using the ICP etching method, the film is formed into a desired taper shape by appropriately adjusting the etching conditions (the amount of power applied to the coil-type electrode, the amount of power applied to the electrode on the substrate side, the electrode temperature on the substrate side, etc.) Can be etched. As an etching gas, Cl ₂ , BCl _Three , SiCl _Four , CCl _Four Chlorine gas or CF represented by _Four , SF ₆ , NF _Three Fluorine gas such as O ₂ Can be used as appropriate.
[0129]
In this embodiment, 150 W of RF (13.56 MHz) power is also applied to the substrate side (sample stage), and a substantially negative self-bias voltage is applied. The electrode area size on the substrate side is 12.5 cm × 12.5 cm, and the coil-type electrode area size (here, the quartz disk provided with the coil) is a disk having a diameter of 25 cm. The W film is etched under this first etching condition so that the end portion of the first conductive layer is tapered. Under the first etching conditions, the etching rate with respect to W is 200.39 nm / min, the etching rate with respect to TaN is 80.32 nm / min, and the selection ratio of W with respect to TaN is about 2.5. Further, the taper angle of W is about 26 ° under this first etching condition. Thereafter, the resist masks 610 to 613 are not removed and the second etching condition is changed, and the etching gas is changed to CF. _Four And Cl ₂ The gas flow ratio is 30/30 (sccm), and 500 W of RF (13.56 MHz) power is applied to the coil-type electrode at a pressure of 1 Pa to generate plasma for about 30 seconds. Etching was performed. 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. CF _Four And Cl ₂ Under the second etching condition in which is mixed, the W film and the TaN film are etched to the same extent. The etching rate for W under the second etching conditions is 58.97 nm / min, and 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, it is preferable to increase the etching time at a rate of about 10 to 20%.
[0130]
In the first etching process, the shape of the mask made of resist is made suitable, and the end portions 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. It becomes. The angle of the tapered portion may be 15 to 45 °.
[0131]
Thus, the first shape conductive layers 615 to 618 (first conductive layers 615 a to 618 a and second conductive layers 615 b to 618 b) composed of the first conductive layer and the second conductive layer by the first etching treatment. Form. The insulating film 607 to be a gate insulating film is etched by about 10 to 20 nm to be a gate insulating film 620 in which a region not covered with the first shape conductive layers 615 to 618 is thinned.
[0132]
Next, a second etching process is performed without removing the resist mask. Here, SF is used as the etching gas. ₆ And Cl ₂ And O ₂ Each gas flow rate ratio is 24/12/24 (sccm), 700 W RF (13.56 MHz) power is applied to the coil type electrode at a pressure of 1.3 Pa, plasma is generated, and etching is performed. For 25 seconds. 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. In the second etching process, the etching rate with respect to W is 227.3 nm / min, the etching rate with respect to TaN is 32.1 nm / min, the selection ratio of W with respect to TaN is 7.1, and the SiON that is the insulating film 620 The etching rate with respect to is 33.7 nm / min, and the selective ratio of W to SiON is 6.83. Thus, SF is used as the etching gas. ₆ Is used, it is possible to suppress a reduction in film thickness because the selection ratio with the insulating film 620 is high. In this embodiment, the insulating film 620 is reduced only by about 8 nm.
[0133]
By this second etching process, the taper angle of W became 70 °. Second conductive layers 621b to 624b are formed by the second etching process. On the other hand, the first conductive layer is hardly etched and becomes the first conductive layers 621a to 624a. Note that the first conductive layers 621a to 624a are approximately the same size as the first conductive layers 615a to 618a. Actually, the width of the first conductive layer may be about 0.3 μm, that is, the entire line width may be receded by about 0.6 μm as compared with that before the second etching process, but the size is hardly changed.
[0134]
In place of the two-layer structure, a three-layer structure in which a 50-nm-thick tungsten film, a 500-nm-thick aluminum and silicon alloy (Al-Si) film, and a 30-nm-thick titanium nitride film are sequentially stacked, As the first etching condition in the first etching process, BCl _Three And Cl ₂ And O ₂ Are used as source gases, each gas flow rate ratio is 65/10/5 (sccm), 300 W RF (13.56 MHz) power is applied to the substrate side (sample stage), and the coil is operated at a pressure of 1.2 Pa. 450 W RF (13.56 MHz) power is applied to the electrode of the mold to generate plasma and perform etching for 117 seconds. The second etching condition in the first etching process is CF _Four And Cl ₂ And O ₂ Each gas flow rate ratio is 25/25/10 (sccm), 20 W RF (13.56 MHz) power is supplied to the substrate side (sample stage), and a coil type electrode is applied at a pressure of 1 Pa. An RF (13.56 MHz) power of 500 W is applied to generate plasma, and etching may be performed for about 30 seconds. As the second etching process, BCl is used. _Three And Cl ₂ Each gas flow rate ratio is 20/60 (sccm), 100 W RF (13.56 MHz) power is applied to the substrate side (sample stage), and 600 W is applied to the coil-type electrode at a pressure of 1.2 Pa. RF (13.56 MHz) power may be input to generate plasma and perform etching.
[0135]
Next, after removing the resist mask, a first doping process is performed to obtain the state of FIG. The doping process may be performed by ion doping or ion implantation. The condition of the ion doping method is that the dose is 1.5 × 10 ¹⁴ atoms / cm ² The acceleration voltage is set to 60 to 100 keV. Typically, phosphorus (P) or arsenic (As) is used as the impurity element imparting n-type conductivity. In this case, the first conductive layer and the second conductive layers 621 to 624 serve as a mask for the impurity element imparting n-type, and the first impurity regions 626 to 629 are formed in a self-aligning manner. The first impurity regions 626 to 629 have 1 × 10 6 ¹⁶ ~ 1x10 ¹⁷ /cm ^Three An impurity element imparting n-type is added in a concentration range of. Here, a region having the same concentration range as the first impurity region is n ^- Also called a region.
[0136]
In this embodiment, the first doping process is performed after removing the resist mask, but the first doping process may be performed without removing the resist mask.
[0137]
Next, as shown in FIG. 8B, masks 631 and 632 made of resist are formed, and a second doping process is performed. The mask 631 is a mask that protects the channel formation region of the semiconductor layer that forms the p-channel TFT of the driver circuit and the surrounding region, and the mask 632 is the channel of the semiconductor layer that forms the TFT (switching TFT) of the pixel portion. It is a mask that protects the formation region and the surrounding region.
[0138]
The condition of the ion doping method in the second doping process is that the dose is 1.5 × 10 5. ¹⁵ atoms / cm ² Then, phosphorus (P) is doped with an acceleration voltage of 60 to 100 keV. Here, impurity regions are formed in a self-aligned manner in each semiconductor layer using the second conductive layer 621b as a mask. Of course, it is not added to the region covered with the masks 631 and 632. Thus, second impurity regions 634, 635, and 636 and third impurity regions 637 and 639 are formed. The second impurity regions 634, 635, and 636 have 1 × 10 ²⁰ ~ 1x10 ^{twenty one} /cm ^Three An impurity element imparting n-type is added in a concentration range of. Here, a region having the same concentration range as the second impurity region is n ⁺ Also called a region.
[0139]
The third impurity region is formed at a lower concentration than the second impurity region by the first conductive layer, and is 1 × 10 6. ¹⁸ ~ 1x10 ¹⁹ /cm ^Three An impurity element imparting n-type is added in a concentration range of. Note that the third impurity region has a concentration gradient in which the impurity concentration increases toward the end portion of the tapered portion because doping is performed by passing the portion of the first conductive layer having a tapered shape. . Here, a region having the same concentration range as the third impurity region is n ^- Also called a region. Further, the region covered with the mask 632 becomes the first impurity region 638 without being doped with the impurity element in the second doping treatment.
[0140]
Next, after removing the resist masks 631 and 632, new resist masks 630, 640, and 633 are formed, and a third doping process is performed as shown in FIG. 8C.
[0141]
In the driver circuit, a fourth impurity region 641 in which an impurity element imparting p-type conductivity is added to the semiconductor layer forming the p-channel TFT and the semiconductor layer forming the storage capacitor by the third doping treatment. Then, a fifth impurity region 643 is formed.
[0142]
The fourth impurity region 641 has 1 × 10 10. ²⁰ ~ 1x10 ^{twenty one} /cm ^Three An impurity element imparting p-type is added in a concentration range of. Note that the fourth impurity region 641 is a region to which phosphorus (P) is added in the previous step (n ^- The concentration of the impurity element imparting p-type is 1.5 to 3 times that of the impurity element, and the conductivity type is p-type. Here, a region having the same concentration range as the fourth impurity region is represented by p. ⁺ Also called a region.
[0143]
The fifth impurity region 643 is formed in a region overlapping with the tapered portion of the second conductive layer 125a. ¹⁸ ~ 1x10 ²⁰ /cm ^Three An impurity element imparting p-type is added in a concentration range of. Here, a region having the same concentration range as the fifth impurity region is represented by p. ^- Also called a region.
[0144]
Through the above steps, impurity regions having n-type or p-type conductivity are formed in each semiconductor layer. The conductive layers 621 to 624 serve as TFT gate electrodes.
[0145]
Next, an insulating film (not shown) that covers substantially the entire surface is formed. In this example, a 50 nm-thickness silicon oxide film was formed by plasma CVD. Of course, this insulating film is not limited to the silicon oxide film, and another insulating film containing silicon may be used as a single layer or a laminated structure.
[0146]
Next, a step of activating the impurity element added to each semiconductor layer is performed. This activation step may be a rapid thermal annealing method (RTA method) using a lamp light source, a method of irradiating a YAG laser or an excimer laser from the back surface, a heat treatment using a furnace, or a combination thereof. By different methods.
[0147]
Further, in this embodiment, an example in which an insulating film is formed before the activation is shown, but an insulating film may be formed after the activation.
[0148]
Next, a first interlayer insulating film 645 made of a silicon nitride film is formed and subjected to heat treatment (heat treatment at 300 to 550 ° C. for 1 to 12 hours) to hydrogenate the semiconductor layer (FIG. 9A). ). Note that the first interlayer insulating film 645 may have a stacked structure including a silicon nitride oxide film and a silicon nitride film formed by a plasma CVD method. This step is a step of terminating dangling bonds in the semiconductor layer with hydrogen contained in the first interlayer insulating film 645. The semiconductor layer can be hydrogenated regardless of the presence of an insulating film (not shown) made of a silicon oxide film. However, in this embodiment, since the material containing aluminum as a main component is used as the second conductive layer, it is important to set the heat treatment conditions that the second conductive layer can withstand in the hydrogenation step. As another means of hydrogenation, plasma hydrogenation (using hydrogen excited by plasma) may be performed.
[0149]
Next, a second interlayer insulating film 646 made of an organic resin film is formed on the first interlayer insulating film 645. In this embodiment, an acrylic resin film having a thickness of 1.6 μm is formed.
[0150]
Further, a barrier film 647 is formed over the second interlayer insulating film 646 in order to prevent degassing such as oxygen generated from the inside of the interlayer insulating film, moisture, and the like from being released. As a material for forming the barrier film 647, specifically, aluminum such as aluminum nitride (AlN), aluminum nitride oxide (AlNO), aluminum oxynitride (AlNO), silicon nitride (SiN), silicon nitride oxide (SiNO), or the like Although an insulating film containing silicon can be used to form a film with a thickness of 0.2 to 1 μm, in this embodiment, a barrier film made of silicon nitride is formed with a film thickness of 0.3 μm by a sputtering method. Note that the sputtering method used here includes a bipolar sputtering method, an ion beam sputtering method, a counter target sputtering method, and the like.
[0151]
Next, contact holes reaching the respective impurity regions are formed. In this embodiment, a plurality of etching processes are sequentially performed. In this embodiment, after etching the second interlayer insulating film using the first interlayer insulating film as an etching stopper, the first interlayer insulating film is etched using the insulating film (not shown) as an etching stopper, and then the insulating film (illustrated). Not etched).
[0152]
Thereafter, wiring is formed using Al, Ti, Mo, W, or the like. In some cases, the pixel electrode of the light-emitting element formed in contact with the wiring can be formed at the same time. As the material of these electrodes and pixel electrodes, it is desirable to use a material having excellent reflectivity such as a film mainly composed of Al or Ag, or a laminated film thereof. In this way, wirings 650 to 657 are formed.
[0153]
As described above, the pixel circuit 706 including the driving circuit 705 including the n-channel TFT 701 and the p-channel TFT 702, the switching TFT 703 including the n-channel TFT, and the current control TFT 704 including the n-channel TFT is the same. It can be formed over a substrate (FIG. 9C). In this specification, such a substrate is referred to as an active matrix substrate for convenience.
[0154]
In the pixel portion 706, the switching TFT 703 (n-channel TFT) has a channel formation region 503 and a first impurity region (n formed outside the conductive layer 623 forming the gate electrode). ^- Region) 638 and a second impurity region (n that functions as a source region or a drain region) ⁺ Region) 635.
[0155]
Further, in the pixel portion 706, the current control TFT 704 (n-channel TFT) includes a channel formation region 504 and a third impurity region (n that overlaps with a part of the conductive layer 624 forming the gate electrode through an insulating film). ^- Region) 639 and a second impurity region (n that functions as a source region or a drain region) ⁺ Region) 636.
[0156]
In the driver circuit 705, the n-channel TFT 701 includes a third impurity region (n that overlaps with the channel formation region 501 and part of the conductive layer 621 forming the gate electrode with an insulating film interposed therebetween. ^- Region) 637 and a second impurity region (n that functions as a source region or a drain region) ⁺ Region) 634.
[0157]
In the driver circuit 705, the p-channel TFT 702 includes a fifth impurity region (p) overlapping with a channel formation region 502 and part of the conductive layer 622 forming the gate electrode with an insulating film interposed therebetween. ^- Region) 643 and a fourth impurity region (p) functioning as a source region or a drain region ⁺ Region) 641.
[0158]
A driving circuit 705 may be formed by appropriately combining these TFTs 701 and 702 to form a shift register circuit, a buffer circuit, a level shifter circuit, a latch circuit, and the like. For example, in the case of forming a CMOS circuit, an n-channel TFT 701 and a p-channel TFT 702 may be complementarily connected.
[0159]
The circuit where reliability is given top priority is a so-called GOLD (Gate-drain Overlapped LDD) structure in which an LDD (LDD: Lightly Doped Drain) region is placed over a gate electrode via a gate insulating film. A certain n-channel TFT 701 structure is suitable.
[0160]
Note that TFTs (n-channel TFTs and p-channel TFTs) in the driver circuit 705 are required to have high driving ability (on current: Ion) and to prevent deterioration due to the hot carrier effect and to improve reliability. In this embodiment, a TFT having a region (GOLD region) in which a gate electrode overlaps with a low concentration impurity region through a gate insulating film is used as a structure effective for preventing deterioration of an on-current value due to hot carriers. .
[0161]
On the other hand, since the switching TFT 703 in the pixel portion 706 requires a low off-current (Ioff), in this embodiment, the gate electrode has a gate insulating film as a TFT structure for reducing the off-current. A TFT having a region (LDD region) that does not overlap with the low concentration impurity region is used.
[0162]
Next, an insulating film is formed. In addition, as a material for forming the insulating film in this embodiment, in addition to an insulating film containing silicon such as silicon nitride and silicon oxynitride, polyimide (including photosensitive polyimide), polyamide, acrylic (including photosensitive acrylic), An organic resin film such as BCB (benzocyclobutene) can also be used.
[0163]
Further, an opening is formed at a position corresponding to the pixel electrode 657 of this insulating film, and an insulating layer 658 is formed (FIG. 10A). Note that in this embodiment, a 1 μm insulating film is formed using photosensitive polyimide, patterning is performed by a photolithography method, and then an insulating layer 658 is formed by performing an etching process.
[0164]
Next, a cathode 659 is patterned on the pixel electrode 657 exposed in the opening of the insulating layer 658 by vapor deposition using a metal mask. As a specific cathode material, it is desirable to be formed of a material having a low work function in order to improve the electron injection property, and a material belonging to an alkali metal or alkaline earth metal or a transition metal containing a rare earth metal is used alone. Used, laminated with other materials, formed with other materials (for example, CsF, BaF, CaF, etc.), and alloys formed with other materials (for example, Al: Mg alloys or Al: Mg) Alloys, Mg: In alloys, etc.) can be used. In this embodiment, CsF is used to form a film with a thickness of 5 nm. Further, an organic compound layer 660 is formed over the cathode 659 by an evaporation method using a metal mask (FIG. 10A). Here, in this embodiment, one of the organic compound layers formed by the organic compounds exhibiting three types of light emission of red, green, and blue is shown, but three types of organic compound layers are formed. The combination of organic compounds to be described will be described in detail below.
[0165]
First, an organic compound layer that emits red light will be described. Specifically, the electron transport layer is an organic compound having an electron transport property, tris (8-quinolinolato) aluminum (hereinafter referred to as Alq). _Three Is formed to a thickness of 40 nm, the blocking layer is formed of a blocking organic compound, bathocuproin (hereinafter referred to as BCP), to a thickness of 10 nm, and the light-emitting layer is a light-emitting layer. 2,3,7,8,12,13,17,18-octaethyl-21H, 23H-porphyrin-platinum (hereinafter referred to as PtOEP) which is an organic compound (hereinafter referred to as host material) And 4,4′-dicarbazole-biphenyl (hereinafter referred to as CBP) to form a film with a thickness of 30 nm, and the hole transport layer is an organic compound having a hole transport property, 4'-bis [N- (1-naphthyl) -N-phenyl-amino] -biphenyl (hereinafter referred to as α-NPD) is formed to a thickness of 40 nm to form a red light-emitting organic compound layer. thing Can do.
[0166]
Here, the case where the organic compound layer for red light emission is formed using five kinds of organic compounds having different functions has been described. However, the present invention is not limited to this, and the organic compound layer for emitting red light is used. Known materials can be used.
[0167]
Next, an organic compound layer that emits green light will be described. Specifically, the electron transport layer is an organic compound having an electron transport property, Alq. _Three Is formed with a film thickness of 40 nm, the blocking layer is formed with BCP, which is a blocking organic compound, with a film thickness of 10 nm, and the light emitting layer uses CBP as a hole transporting host material to emit light. Tris (2-phenylpyridine) iridium (Ir (ppy)) _Three ) And co-evaporated to form a film with a film thickness of 30 nm, and the hole transport layer is an organic compound that emits green light by forming a film with a thickness of 40 nm of α-NPD, which is a hole transporting organic compound. Compounds can be formed.
[0168]
Here, the case where the organic compound layer that emits green light is formed using four types of organic compounds having different functions has been described, but the present invention is not limited to this, and is known as an organic compound that emits green light. These materials can be used.
[0169]
Next, an organic compound layer that emits blue light will be described. Specifically, the electron transport layer is an organic compound having an electron transport property, Alq. _Three Is formed with a film thickness of 40 nm, the blocking layer is a blocking organic compound, BCP is formed with a film thickness of 10 nm, and the light emitting layer is a light emitting and hole transporting organic compound. By forming α-NPD with a thickness of 40 nm, an organic compound layer emitting blue light can be formed.
[0170]
Here, the case where the organic compound layer for blue light emission is formed using three types of organic compounds having different functions has been described, but the present invention is not limited to this, and is known as an organic compound exhibiting blue light emission. These materials can be used.
[0171]
By forming an organic compound layer having a combination as described above on the anode, an organic compound layer exhibiting red light emission, green light emission, and blue light emission can be formed in the pixel portion.
[0172]
In this embodiment, the material for forming the organic compound layer 660 and the material for forming the protective film 661 are co-evaporated on each of the organic compound layers to form a mixed region. In FIG. 10B, a mixed region is indicated by a broken line at the interface between the organic compound layer and the protective film. Note that the mixed region is formed to a thickness of 1 to 2 nm so as to cover the organic compound layer 660 and the insulating layer 658. For example, when the organic compound layer 660 is formed of an organic compound layer that emits red light and gold is used as the metal material for forming the protective film 661, α-NPD and gold that form the hole transport layer are used. Are co-deposited to form a mixed region.
[0173]
A protective film 661 is formed on the mixed region. Note that as the metal material for forming the protective film 661, specifically, a conductive film having a visible light transmittance of 70 to 100% and a work function of 4.5 to 5.5 is used. Further, since the metal film is often opaque to visible light, it is formed with a thickness of 0.5 to 5 nm. In this embodiment, as described above, gold is used and a film thickness of 4 nm is formed by vapor deposition.
[0174]
Next, an anode 662 is formed. In the present invention, since the anode 662 is an electrode that transmits light generated in the organic compound layer 660, the anode 662 is formed using a light-transmitting material. The anode 662 is an electrode for injecting holes into the organic compound layer 660, and thus needs to be formed using a material having a high work function. In this embodiment, as a material for forming the anode 662, an indium tin oxide (ITO) film or a transparent conductive film in which 2 to 20% zinc oxide (ZnO) is mixed with indium oxide is formed by sputtering to 100 nm. The film is used to have a film thickness of Note that the anode 662 can be formed using another known material (IZO, IDIXO, or the like) as long as it is a transparent conductive film having a high work function. Further, when forming the anode 662, the substrate is cooled from the back side of the substrate or the substrate temperature is maintained at about 80 ° C., so that the heat damage given to the organic compound layer at the time of sputtering is reduced. May be.
[0175]
Thus, as shown in FIG. 10B, an insulating layer formed in a gap between the pixel electrode 657 electrically connected to the current control TFT 704 and the pixel electrode (not shown) adjacent to the pixel electrode 657. 658, a cathode 659 formed over the pixel electrode 657, an organic compound layer 660 formed over the cathode 659, a mixed region formed over the organic compound layer 660 and the insulating layer 658, and formed over the mixed region An element substrate having a light-emitting element 663 including the protective film 661 and the anode 662 formed over the protective film 661 can be formed.
[0176]
Note that in the manufacturing process of the light-emitting device in this embodiment, a source line is formed using a material for forming a gate electrode and is electrically connected to a source region and a drain region because of a circuit configuration and a process. Although the scanning lines are formed using the material for forming the wiring, it is possible to use different materials.
[0177]
In the light-emitting device of the present invention, a method in which a predetermined voltage based on a video signal input from a source line is input to the gate of the current control TFT 704 (hereinafter referred to as a constant voltage driving method), or a source signal The present invention can be implemented in any case of a method in which a predetermined current based on a video signal input from a line is input from the current control TFT 704 (hereinafter referred to as a constant current driving method). In this embodiment, the driving voltage of the TFT is 1.2 to 10V, preferably 2.5 to 5.5V.
[0178]
Further, FIG. 15 illustrates a case where part of the structure of the light-emitting device described in FIG.
[0179]
In FIG. 15, a pixel electrode 1501 is formed in the same manner as in FIG. Then, an insulating layer 1502 is formed so as to cover the end portion. Here, an inorganic insulating material containing silicon such as silicon nitride, silicon oxide, or silicon oxynitride is used as a material for forming the insulating layer 1502. The film is formed with a thickness of 1 to 0.3 μm.
[0180]
Specifically, a silicon nitride film is formed with a thickness of 0.2 μm by a sputtering method.
[0181]
As described above, when the insulating layer 1502 is formed using an inorganic insulating material, moisture, organic gas, and the like released from the material can be reduced as compared with the case where the insulating layer 1502 is formed using an organic resin film.
[0182]
FIG. 15B is a top view of part of the pixel portion 1511 in the case of having the structure of FIG. A plurality of pixels 1512 are formed in the pixel portion 1511. The top view shown here shows a state where the insulating layer 1502 in FIG. 15A is formed. That is, the insulating layer 1502 is formed so as to cover the source line 1513, the scanning line 1514, and the current supply line 1515. A region a (1503) where a connection portion between the pixel electrode and the TFT is formed below is also covered with an insulating layer 1502.
[0183]
15B is a cross-sectional view taken along a dotted line AA ′ of the pixel portion 1511 illustrated in FIG. 15B, and includes a cathode 1504, an organic compound layer 1505, a mixed region (not shown), and a protective film 1506 over the pixel electrode 1501. The formed state is shown in Fig. 15C, where organic compound layers made of the same material are formed in the vertical direction with respect to the paper surface, and organic compound layers made of different materials in the horizontal direction. Is formed.
[0184]
For example, an organic compound layer (R) 1505a that emits red light is formed in the pixel (R) 1512a in FIG. 15B, and an organic compound layer (G) 1505b that emits green light is formed in the pixel (G) 1512b. Thus, an organic compound layer (B) 1505c that emits blue light is formed in the pixel (B) 1512c. A protective film is formed on each of these organic compound layers via a mixed region. Note that the insulating layer 1502 serves as a margin for forming the organic compound layer, and the deposition position of the organic compound layer is slightly shifted, so that an organic compound layer made of a different material is formed over the insulating layer 1502 as illustrated in FIG. Even if they overlap, there is no problem if it is on the insulating layer 1502.
[0185]
Further, FIG. 15B is a cross-sectional view taken along a dotted line BB ′ of the pixel portion 1511 shown in FIG. 15B, and shows a state where the cathode 1504 and the organic compound layer 1505 are formed over the pixel electrode 1501 as in FIG. 15 (D).
[0186]
Note that the pixel cut along the dotted line BB ′ has the structure shown in FIG. 15D because an organic compound layer (R) 1505 a that emits red light similar to the pixel (R) 1512 a is formed.
[0187]
Further, when the display of the pixel portion is in operation (in the case of moving image display), the background is displayed by the pixel emitting light, and the character display is performed by the pixel where the light emitting element does not emit light. However, when the video display of the pixel portion is stationary for a certain period or longer (referred to as standby in this specification), the display method is switched (reversed) to save power. It is good to leave. Specifically, a character is displayed by a pixel from which the light emitting element emits light (also referred to as character display), and a background is displayed by a pixel from which the light emitting element does not emit light (also referred to as background display).
[0188]
Example 4
In this embodiment, a light-emitting device having a part of the structure different from that shown in Embodiment 3 will be described with reference to FIG.
[0189]
In FIG. 11A, a wiring 670 is formed instead of the pixel electrode formed in FIG. Thereafter, a third interlayer insulating film 671 is formed so as to cover the wiring 670. Note that the third interlayer insulating film 671 formed here can be formed using the material used when the first and second interlayer insulating films are formed.
[0190]
Next, an opening is formed at a position overlapping the wiring 670 of the third interlayer insulating film 671, and then a pixel electrode 672 is formed. Note that as a material for forming the pixel electrode 672, a material used for forming the wiring 670 can be used.
[0191]
Further, an insulating layer 673 is formed so as to cover an end portion of the pixel electrode 672, and a cathode 674 and an organic compound layer 675 are formed over the pixel electrode 672. Note that as a material for forming the insulating layer 673, a photosensitive polyimide is used to form a film having a thickness of 1 μm as in the third embodiment.
[0192]
Through the above steps, the protective film 676 and the anode 677 are formed over the organic compound layer 675 as illustrated in FIG. 11B, whereby the light-emitting element 678 is completed. Note that a manufacturing process after the pixel electrode 672 is formed can be formed by a method similar to that in Embodiment 3, and thus the description thereof is omitted.
[0193]
Note that with the structure as shown in this embodiment, the area of the pixel electrode can be increased, so that the aperture ratio can be further improved in the upward emission type light emitting device as in the present invention. it can.
[0194]
Further, FIG. 16 illustrates a case where part of the structure of the light-emitting device described in FIG.
[0195]
In FIG. 16, a pixel electrode 1601 is formed in the same manner as in FIG. Then, an insulating layer 1602 is formed so as to cover the end portion, but here, unlike that shown in FIG. 11B, inorganic insulation containing silicon such as silicon nitride, silicon oxide, or silicon oxynitride It forms with the film thickness of 0.1-0.3 micrometer with materials.
[0196]
Specifically, a silicon nitride film is formed with a thickness of 0.2 μm by a sputtering method.
[0197]
As described above, when the insulating layer 1602 is formed using an inorganic insulating material, moisture, organic gas, and the like released from the material can be reduced as compared with the case where the insulating layer 1602 is formed using an organic resin film. Note that the cathode 1604, the organic compound layer 1605, the protective film 1606, and the anode 1607 which are formed after the insulating layer 1602 can be formed in a manner similar to that illustrated in FIG.
[0198]
(Example 5)
In this embodiment, a pixel structure of a pixel portion of a light emitting device driven by a constant current driving method will be described. The pixel 1310 shown in FIG. 13 includes a signal line Si (one of S1 to Sx), a first scanning line Gj (one of G1 to Gy), and a second scanning line Pj (P1 to Py). 1) and a power supply line Vi (one of V1 to Vx). The pixel 1310 includes Tr1, Tr2, Tr3, Tr4, a light emitting element 1311, and a storage capacitor 1312.
[0199]
The gates of Tr3 and Tr4 are both connected to the first scanning line Gj. One of the source and drain of Tr3 is connected to the signal line Si, and the other is connected to the source of Tr2. One of the source and drain of Tr4 is connected to the source of Tr2, and the other is connected to the gate of Tr1. That is, one of the source and drain of Tr3 and one of the source and drain of Tr4 are connected.
[0200]
The source of Tr1 is connected to the power supply line Vi, and the drain is connected to the source of Tr2. The gate of Tr2 is connected to the second scanning line Pj. The drain of Tr2 is connected to a light emitting element 1311 formed on the pixel electrode through the pixel electrode. The light-emitting element 1311 includes a cathode, an anode, and an organic compound layer provided between the cathode and the anode. A constant voltage is applied to the anode of the light emitting element 1311 by an external power source.
[0201]
Note that Tr3 and Tr4 may be either n-channel TFTs or p-channel TFTs. However, Tr3 and Tr4 have the same polarity. Tr1 may be either an n-channel TFT or a p-channel TFT. Tr2 may be either an n-channel TFT or a p-channel TFT. However, in the present invention, since the electrode connected to Tr2 is a cathode, Tr2 is preferably formed of an n-channel TFT.
[0202]
The storage capacitor 1312 is formed between the gate and source of Tr1. The storage capacitor 1312 is a voltage between the gate and the source of Tr1 (V _GS ) Is more reliably maintained, but is not necessarily provided.
[0203]
In the pixel shown in FIG. 13, the current supplied to the source line is controlled by a current source included in the signal line driver circuit.
[0204]
In addition, the structure of this invention can be implemented in combination freely with any structure of Example 1-4.
[0205]
(Example 6)
In this example, an external view of a light-emitting device of the present invention will be described with reference to FIG. 12A is a top view illustrating the light-emitting device, and FIG. 12B is a cross-sectional view taken along line AA ′ in FIG. 12A. 1201 indicated by a dotted line is a source signal side driving circuit, 1202 is a pixel portion, and 1203 is a gate signal side driving circuit. 1204 is a sealing substrate, 1205 is a sealant, and the inside surrounded by the sealant 1205 is a space.
[0206]
Reference numeral 1208 denotes a wiring for transmitting signals input to the source signal side drive circuit 1201 and the gate signal side drive circuit 1203, and a video signal and a clock signal are received from an FPC (flexible printed circuit) 1209 which is an external input terminal. receive. 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 a light-emitting device body but also a state in which an FPC or a PWB is attached thereto.
[0207]
Next, a cross-sectional structure will be described with reference to FIG. A driver circuit and a pixel portion are formed over the substrate 1210. Here, a source signal side driver circuit 1201 and a pixel portion 1202 are shown as driver circuits.
[0208]
Note that the source signal side driver circuit 1201 is a CMOS circuit in which an n-channel TFT 1213 and a p-channel TFT 1214 are combined. 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, but this is not always necessary, and it can be formed outside the substrate.
[0209]
The pixel portion 1202 is formed of a plurality of pixels including a current control TFT 1211 and a pixel electrode 1212 electrically connected to the drain thereof.
[0210]
An insulating layer 1213 is formed on both ends of the pixel electrode 1212, a cathode 1214 is formed on the pixel electrode 1212, and an organic compound layer 1215 is formed on the cathode 1214. Further, a mixed region (not shown) is formed at the interface between the organic compound layer 1215 and the protective film 1216, and an anode 1217 is formed on the protective film 1216. Thus, a light emitting element 1218 including the cathode 1214, the organic compound layer 1215, the protective film 1216, and the anode 1217 is formed.
[0211]
The anode 1217 also functions as a wiring common to all pixels, and is electrically connected to the FPC 1209 via the connection wiring 1208.
[0212]
In addition, in order to seal the light emitting element 1218 formed over the substrate 1210, the sealing substrate 1204 is attached with a sealant 1205. Note that a spacer made of a resin film may be provided in order to secure a gap between the sealing substrate 1204 and the light emitting element 1218. A space 1207 inside the sealing agent 1205 is filled with an inert gas such as nitrogen. Note that an epoxy resin is preferably used as the sealant 1205. Further, the sealant 1205 is desirably a material that does not transmit moisture and oxygen as much as possible. Further, a substance having an effect of absorbing oxygen and water may be contained in the space 1207.
[0213]
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 constituting the sealing substrate 1204 in addition to a glass substrate or a quartz substrate. be able to. In addition, after the sealing substrate 1204 is bonded using the sealing agent 1205, the sealing substrate 1204 can be further sealed with a sealing agent so as to cover the side surface (exposed surface).
[0214]
By enclosing the light-emitting element in the space 1207 as described above, the light-emitting element can be completely blocked from the outside, and a substance that promotes deterioration of the organic compound layer such as moisture and oxygen can be prevented from entering from the outside. Can do. Therefore, a highly reliable light-emitting device can be obtained.
[0215]
In addition, the structure of a present Example can be implemented in combination freely with any structure shown in Examples 1-5.
[0216]
(Example 7)
Since a light-emitting device using a light-emitting element is a self-luminous type, it is superior in visibility in a bright place and has a wide viewing angle as compared with a liquid crystal display device. Therefore, various electric appliances can be completed using the light-emitting device of the present invention.
[0217]
As an electric appliance manufactured using the light emitting device manufactured according to the present invention, a video camera, a digital camera, a goggle type display (head mounted display), a navigation system, a sound reproduction device (car audio, audio component, etc.), a notebook type personal computer Computers, game machines, portable information terminals (mobile computers, mobile phones, portable game machines, electronic books, etc.), image playback devices equipped with recording media (specifically, playback of recording media such as digital video discs (DVDs)) And a device provided with a display device capable of displaying the image). In particular, a portable information terminal that often has an opportunity to see a screen from an oblique direction emphasizes a wide viewing angle, and thus it is preferable to use a light emitting device having a light emitting element. Specific examples of these electric appliances are shown in FIG.
[0218]
FIG. 14A illustrates a display device, which includes a housing 2001, a support base 2002, a display portion 2003, a speaker portion 2004, a video input terminal 2005, and the like. It is manufactured by using the light emitting device manufactured according to the present invention for the display portion 2003. Since a light-emitting device having a light-emitting element is a self-luminous type, a backlight is not necessary and a display portion thinner than a liquid crystal display device can be obtained. The display devices include all information display devices for personal computers, for receiving TV broadcasts, for displaying advertisements, and the like.
[0219]
FIG. 14B shows a digital still camera, which includes a main body 2101, a display portion 2102, an image receiving portion 2103, operation keys 2104, an external connection port 2105, a shutter 2106, and the like. It is manufactured by using the light emitting device manufactured according to the present invention for the display portion 2102.
[0220]
FIG. 14C illustrates a laptop personal computer, which includes a main body 2201, a housing 2202, a display portion 2203, a keyboard 2204, an external connection port 2205, a pointing mouse 2206, and the like. It is manufactured by using the light emitting device manufactured according to the present invention for the display portion 2203.
[0221]
FIG. 14D illustrates a mobile computer, which includes a main body 2301, a display portion 2302, a switch 2303, operation keys 2304, an infrared port 2305, and the like. It is manufactured by using the light emitting device manufactured according to the present invention for the display portion 2302.
[0222]
FIG. 14E shows a portable image reproducing device (specifically, a DVD reproducing device) provided with a recording medium, which includes a main body 2401, a housing 2402, a display portion A2403, a display portion B2404, and a recording medium (DVD or the like). A reading unit 2405, operation keys 2406, a speaker unit 2407, and the like are included. The display portion A 2403 mainly displays image information and the display portion B 2404 mainly displays character information. The light-emitting device manufactured according to the present invention is used for the display portions A, B 2403 and 2404. Note that an image reproducing device provided with a recording medium includes a home game machine and the like.
[0223]
FIG. 14F illustrates a goggle type display (head mounted display), which includes a main body 2501, a display portion 2502, and an arm portion 2503. It is manufactured by using the light emitting device manufactured according to the present invention for the display portion 2502.
[0224]
FIG. 14G illustrates a video camera, which includes a main body 2601, a display portion 2602, a housing 2603, an external connection port 2604, a remote control reception portion 2605, an image receiving portion 2606, a battery 2607, an audio input portion 2608, operation keys 2609, and an eyepiece. Part 2610 and the like. It is manufactured by using the light emitting device manufactured according to the present invention for the display portion 2602.
[0225]
Here, FIG. 14H shows a mobile phone, which includes a main body 2701, a housing 2702, a display portion 2703, an audio input portion 2704, an audio output portion 2705, operation keys 2706, an external connection port 2707, an antenna 2708, and the like. It is manufactured by using the light emitting device manufactured according to the present invention for the display portion 2703. Note that the display portion 2703 can reduce power consumption of the mobile phone by displaying white characters on a black background.
[0226]
If the emission luminance of the organic material is increased in the future, the light including the output image information can be enlarged and projected by a lens or the like and used for a front type or rear type projector.
[0227]
In addition, the electric appliances often display information distributed through electronic communication lines such as the Internet or CATV (cable television), and in particular, opportunities to display moving image information are increasing. Since the response speed of the organic material is very high, the light-emitting device is preferable for displaying moving images.
[0228]
In addition, since the light emitting portion of the light emitting device consumes power, it is preferable to display information so that the light emitting portion is minimized. Therefore, when a light emitting device is used for a display unit mainly including character information, such as a portable information terminal, particularly a mobile phone or a sound reproduction device, it is driven so that character information is formed by the light emitting part with the non-light emitting part as the background. It is preferable to do.
[0229]
As described above, the applicable range of a light-emitting device manufactured using the manufacturing method of the present invention is so wide that electric appliances in various fields can be manufactured using the light-emitting device of the present invention. In addition, the electric appliance of the present embodiment can be completed by using the light emitting device manufactured by performing the first to sixth embodiments.
[0230]
(Example 8)
Furthermore, the light-emitting device of the present invention can have the structure shown in FIG.
[0231]
As an insulating layer 1814 (referred to as a bank, a partition, a barrier, a bank, or the like) that covers an end portion of the cathode 1803 (and the wiring 1813), an inorganic material (silicon oxide, silicon nitride, silicon oxynitride, or the like), photosensitive or non-photosensitive Organic materials (polyimide, acrylic, polyamide, polyimide amide, resist or benzocyclobutene), or a laminate of these can be used. For example, when positive photosensitive acrylic is used as the organic resin material As shown in FIG. 19, it is preferable that the radius of curvature at the end of the insulator is 0.2 to 2 μm and that the contact surface has a curved surface with an angle of 35 degrees or more.
[0232]
In addition, as a material used for the organic compound layer 1804 of the light-emitting element 1802, a material that emits white light can be used. In this case, it is formed by vapor deposition, for example, from the cathode 1803 side, TPD (aromatic diamine), p-EtTAZ, Alq _Three , Alq partially doped with Nile Red, a red luminescent dye _Three , Alq _Three May be sequentially stacked.
[0233]
Further, a passivation film 1815 can be formed using an insulating material over the anode 1807 of the light-emitting element 1802. Note that as a material used for the passivation film 1815 at this time, in addition to a silicon nitride film formed using Si as a target, a stacked film formed by sandwiching a hygroscopic material between silicon nitride films is used in a sputtering method. it can. Further, a DLC film (diamond-like carbon film), carbon nitride (CxNy), or the like can be used.
[0234]
【The invention's effect】
In the present invention, an element having a higher aperture ratio can be formed by manufacturing a top emission type light emitting device as compared with a bottom emission type light emitting device. In manufacturing a top emission type light emitting device, an electrode (lower electrode) connected to a TFT is used as a cathode, and an anode serving as a light extraction electrode (upper electrode) is formed on an organic compound layer formed on the cathode. For this reason, a transparent conductive film such as ITO or IZO that has already been put into practical use can be used as an anode material, and a light emitting element having a different element structure from a conventional top emission type light emitting device can be manufactured.
[0235]
As a result, in the case of an element structure that extracts light from the cathode side, which is the upper electrode, sufficient film formability is required to maintain the function as a cathode, whereas translucency as a light extraction electrode is required. Therefore, it is necessary to form the film with a very thin film, so that it is possible to solve the contradiction that occurs to satisfy both conditions.
[0236]
Furthermore, by providing a protective film at the interface between the organic compound layer and the anode, it is possible to prevent damage to the organic compound layer, which is a problem when forming the anode.
[Brief description of the drawings]
1A and 1B illustrate an element structure of a light-emitting device of the present invention.
2A and 2B illustrate a manufacturing process of a light-emitting device of the present invention.
3A and 3B illustrate a manufacturing process of a light-emitting device of the present invention.
4A and 4B illustrate an element structure of a light-emitting device of the present invention.
FIG. 5 illustrates an element structure of a low molecular light-emitting device of the present invention.
FIG. 6 illustrates an element structure of a polymer light-emitting device of the present invention.
7A and 7B illustrate a manufacturing process of a light-emitting device of the present invention.
8A and 8B illustrate a manufacturing process of a light-emitting device of the present invention.
9A and 9B illustrate a manufacturing process of a light-emitting device of the present invention.
10A and 10B illustrate a manufacturing process of a light-emitting device of the present invention.
11A to 11C illustrate a manufacturing process of a light-emitting device of the present invention.
12A and 12B illustrate an element structure of a light-emitting device of the present invention.
FIG. 13 illustrates a circuit configuration that can be used in the present invention.
FIG. 14 illustrates an example of an electric appliance.
FIG. 15 illustrates an element structure of a light-emitting device of the present invention.
FIG. 16 illustrates an element structure of a light-emitting device of the present invention.
FIG. 17 shows a film formation chamber.
FIG. 18 is a diagram showing a conventional example.
FIG. 19 illustrates an element structure of a light-emitting device of the present invention.

Claims (8)

A cathode formed on a substrate; an organic compound layer formed on the cathode; a protective film made of a metal material formed on the organic compound layer; and a translucency formed on the protective film. Yes, and a light-emitting element having an anode for extracting light,
Between the organic compound layer and the protective film, there is a mixed region in which an organic compound constituting the layer closest to the protective film of the organic compound layer and a metal material constituting the protective film are mixed. A light emitting device. A TFT provided on an insulating surface;
An interlayer insulating film formed on the TFT;
A barrier film formed on the interlayer insulating film;
A pixel electrode formed on and in contact with the barrier film;
An insulating film formed to cover an end of the pixel electrode;
A cathode formed on the pixel electrode;
Anode for extracting an organic compound layer formed on the cathode, a protective film made of a metal material formed on the organic compound layer, have a translucent formed on the protective film, the light A light emitting device comprising:
The barrier film is made of an insulating film of aluminum nitride, aluminum nitride oxide, aluminum oxynitride, silicon nitride, or silicon nitride oxide,
The TFT has a source region and a drain region,
The pixel electrode is electrically connected to either the source region or the drain region through an opening formed in the interlayer insulating film and the barrier film,
Having a mixed region between the organic compound layer and the protective film;
The light-emitting device, wherein the mixed region includes an organic compound that forms a layer of the organic compound layer that is closest to the protective film, and a metal material that forms the protective film. In claim 1 or claim 2,
The organic compound layer includes a first layer made of an organic compound,
A second layer made of an organic compound different from the substance constituting the first layer,
A light emission characterized by having a mixed layer containing an organic compound constituting the first layer and an organic compound constituting the second layer between the first layer and the second layer apparatus. In any one of Claims 1 to 3,
The mixed region has a mean film thickness of 0.5 to 10 nm. In any one of Claims 1 thru | or 4,
The light-emitting device, wherein the metal material forming the protective film is gold, silver, or platinum. In any one of Claims 1 thru | or 5,
The light emitting device, wherein the anode is made of a transparent conductive film. In any one of Claims 1 thru | or 6,
The light-emitting device, wherein the protective film and the anode have a transmittance of 70 to 100% with respect to visible light.   An electric appliance comprising the light emitting device according to any one of claims 1 to 7.

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