JP4335045B2 - Inorganic electroluminescent element manufacturing method and inorganic electroluminescent element - Google Patents

Description

  The present invention relates to an inorganic electroluminescent element used in a flat display device, a surface light source, and the like, and a manufacturing method thereof.

  Since a phenomenon in which the phosphor emits light by applying a voltage to the phosphor, so-called electroluminescence (EL) was discovered in 1936, such a phosphor can be used as a surface light source or an image display device (display). Much research and development has been conducted for application to (devices), and various configurations of EL elements have been proposed and studied so far. For example, Patent Document 1 describes a dispersion type EL element (FIG. 1) and a thin film type EL element (FIG. 2) driven by alternating current.

  The dispersion type EL element is obtained by laminating a light emitting layer, an insulating layer and the like in which electrodes and phosphor particles are dispersed and supported by a dielectric material on a substrate. For example, an AC drive type dispersion type EL element in which a light emitting layer containing phosphor particles such as ZnS: Cu and an insulating thick film are stacked is used for a backlight light source or a signboard of a liquid crystal display. Further, Patent Document 1 discloses a dispersion type EL element using multilayer structured particles as a light emitting layer in order to realize a higher light emission extraction rate and the like than before (FIGS. 3-6).

  On the other hand, the thin film EL element is obtained by laminating an electrode, a light emitting layer made of a phosphor thin film, and an insulating layer on a substrate. At present, from the viewpoint of luminance characteristics and stability, an AC drive type thin film EL element in which an insulator thin film is inserted is applied to various display devices and put into practical use.

FIG. 5 is a cross-sectional view showing the basic structure of a double insulating layer structure thin film EL element. This EL element has a multilayer thin film structure, a transparent glass substrate 21, a first transparent electrode 22 such as ITO (indium tin oxide) formed on the substrate 21, and a first thin film insulating layer. 23, a thin film light emitting layer 24 made of a phosphor thin film exhibiting electroluminescence such as ZnS: Mn, a second thin film insulating layer 25, and a second electrode 26 such as an Al thin film. The first and second insulating layers are transparent dielectric thin films containing Y ₂ O ₂ , Ta ₂ O ₅ , Al ₂ O ₃ , Si ₃ N ₄ , BaTiO ₃ , SrTiO _3, etc. It is formed by a method such as sputtering or vapor deposition. Such an insulating layer limits the current flowing in the light emitting layer, contributes to the improvement of the operation stability and light emitting characteristics of the EL element, and protects the light emitting layer from contamination of moisture, harmful ions, etc. This is to improve the reliability of the element. Note that the role of the insulating layer is basically the same in the dispersion type EL element.

  Such an EL device has several problems in practical use. First, since it is difficult to eliminate the breakdown of elements over a wide area, the yield is lowered. Second, since a voltage is dividedly applied to the insulating layer, a driving voltage applied to an element necessary for light emission becomes high.

  Among these problems, it is desired to employ a material having a good withstand voltage characteristic for the dielectric breakdown of the element. As for the driving voltage for emitting light, it is desirable to increase the capacity of the insulating layer as much as possible in order to reduce the division of the voltage applied to the insulating layer. In particular, in an AC driven inorganic EL element, the amount of current flowing through the light emitting layer that contributes to light emission is substantially proportional to the capacity of the insulating layer. Therefore, by increasing the capacity of the insulating layer, the driving voltage can be lowered and the light emission luminance can be increased. Therefore, the insulating layer is required to have a high withstand voltage and a large capacity.

  By the way, a performance index ε · Ebd value obtained by the product of the dielectric constant ε and the dielectric breakdown electric field Ebd is widely adopted as an index indicating the quality of the insulating layer material. In a practical EL element, the performance index ε · Ebd value of the insulating layer is required to be at least about three times the performance index ε · Ebd value of the ZnS light emitting layer (see Non-Patent Document 1). Here, in the case of an insulator material having a very large dielectric breakdown electric field Ebd value, it is possible to increase the capacity of the insulating layer by using a very thin film thickness even if the dielectric constant ε is small. Is possible. However, since a large area is actually required for a display device and a surface light source, it is extremely difficult to eliminate defects such as minute dirt and adhesion of fine particles over such an area. Therefore, for example, an insulating layer having a film thickness of several hundreds of inches or less cannot be employed.

From such a viewpoint, it has been studied to employ a thin film having a high dielectric constant. For example, an attempt has been made to drive at a low voltage by adopting PbTiO ₃ formed by sputtering as an insulating layer (see Non-Patent Document 2). The sputtered PbTiO ₃ film has a dielectric constant of 190 at the maximum and exhibits a dielectric strength of 0.5 MV / cm. However, since the substrate temperature reaches as high as 600 ° C. when forming the PbTiO ₃ film, the materials that can be used as the substrate are limited, which is not practical.

  Furthermore, in a thin-film inorganic EL element that employs an insulating layer having a relatively high dielectric constant, when dielectric breakdown occurs, it does not become a self-healing type breakdown that completes the breakdown leaving a minute breakdown hole, Prone to propagating destruction. Such a tendency is particularly fatal in applications such as display devices.

  As described above, even when a thin film insulating layer having a large figure of merit ε · Ebd value is employed, it is difficult to achieve stability against all of voltage reduction, high luminance, and dielectric breakdown. In addition, since the specific resistance of the ITO film used as the transparent electrode is not sufficiently small, dielectric breakdown tends to occur at the edge portion when the ITO film is used thick. In order to avoid this, the ITO film needs to have a thickness of, for example, 2 microns or less. However, in this case, the electric resistance cannot be sufficiently reduced. Therefore, it has been difficult to realize a display device having a large area or a large display screen.

  As described above, in the conventional thin film EL element, the constituent material itself is expensive, the yield is low, and an expensive driving circuit with a high withstand voltage is required. I had to.

  In order to solve such problems, Patent Document 2 discloses that an EL element using a high dielectric thick film as a first insulating layer is formed on a ceramic substrate having excellent heat resistance. ing. As shown in FIG. 6, the EL element includes a ceramic substrate 31, a first electrode 32 made of a noble metal such as Pt formed on the substrate 31, and a first insulating layer 33 made of a high dielectric thick film. A thin film light emitting layer 34 made of a phosphor thin film such as ZnS: Mn, a thin film second insulating layer 35, and a transparent second electrode 36 such as ITO. As the first insulating layer 33, a high dielectric thick film such as a Pb-based composite perovskite formed by a green sheet method is used. In Patent Document 2, by using such a configuration for an EL element, stability is increased and higher luminance and a constant voltage are achieved as compared with a double insulating layer structure using a conventional glass substrate. Yes.

  However, even such an element has some practical problems. That is, in the EL element manufacturing method in Patent Document 2, a green sheet method is used when forming a high dielectric thick film. In the green sheet method, the particles of the thick film raw material are kneaded with the binder and applied to the substrate. Therefore, it is necessary to scatter the binder after drying. At that time, pores are generated, and there is a limit to suppressing them. Therefore, it is difficult to form a dense thick film by the green sheet method. Therefore, it is not appropriate to use such a thick film as an insulating layer from the viewpoint of withstand voltage. In addition, in order to make the thick film dense, it is necessary to sinter at a high temperature of about 900 ° C. to 1000 ° C. At this time, the thick film reacts with the ceramic substrate, or the thick film and the ceramic substrate. There is also a problem that cracks occur in the thick film due to the difference in thermal expansion coefficient. Furthermore, according to the green sheet method, irregularities are formed on the surface of the thick film. Even if the surface is polished to eliminate this, the pores are exposed on the polished surface, so that the unevenness cannot be eliminated. However, if the first insulating layer made of a high dielectric thick film has irregularities, the light emitting layer made of the phosphor thin film cannot be formed uniformly. Therefore, the light emitting layer is liable to cause dielectric breakdown, and it is difficult to configure an inorganic EL element.

By the way, Patent Document 3 discloses forming a dielectric layer of a ceramic dielectric thick film capacitor by a gas deposition method. The gas deposition method is a film forming method in which ultrafine particles of a material are suspended in a gas to be aerosolized and sprayed and deposited on a substrate at high speed via a spray nozzle. The gas deposition method is also described in detail in Non-Patent Document 4.
International Publication WO02 / 080626 (Figure 1-6) Japanese Examined Patent Publication No. 7-44072 Japanese Patent No. 3084286 Howard, “The Importance of Insulator Properties in a Thin-Film Electroluminescent Device”, IEEE TRANSACTIONS ON ELECTRON DEVICES, 1977 July ED-24, No. 7, p. 903-908 OKAMOTO and 2 others, “Low-Threshold-Voltage Thin-Film Electroluminescent Devices”, IEEE TRANSACTIONS ON ELECTRON DEVICES, 1981 June, ED-28, No. 6, p. 698-702 Japan Display '83, P.76 (1983) Seiichiro Kashu, et al., “Gas Deposition of Ultrafine Particles” (vacuum, 1992, Vol. 35, No. 7, pages 649-653)

  Therefore, in view of the above points, a first object of the present invention is to provide a highly reliable inorganic electroluminescent element. A second object of the present invention is to provide a method for manufacturing an inorganic EL element that can be applied to inexpensive glass substrates, plastic substrates, films, and the like.

In order to solve the above problems, a method for manufacturing an inorganic electroluminescent element according to the present invention includes a step (a) of forming a first electrode layer having a predetermined pattern on a substrate, and the first electrode layer includes: A powder of a material having an average particle size of 0.1 μm to 5 μm and having a dielectric property is sprayed from a nozzle using an aerosol deposition method toward a formed substrate, and a velocity of 50 m / s to 450 m / s. The step (b) of forming a first insulating layer having an average crystal grain size of 100 nm or less and a film density of 90% or more by colliding with and depositing on the first electrode layer ; A step (c) of forming a light emitting layer on the insulating layer using particles exhibiting electroluminescence or a precursor thereof, and a step (d) of forming a second electrode layer on the light emitting layer. It has.

Moreover, the inorganic electroluminescent element according to the present invention is a substrate, a first electrode layer formed on the substrate, and a thick film having a dielectric property, wherein the first electrode layer is formed. A first powder having an average crystal grain size of 100 nm or less and a film density of 90% or more is formed by spraying and depositing a powder of a dielectric material on a substrate using an aerosol deposition method . An insulating layer, a light emitting layer exhibiting electroluminescence formed on the first insulating layer, and a second electrode layer formed on the light emitting layer.

  According to the present invention, a dense first insulating layer having a high withstand voltage is formed by spraying and depositing a powder of a dielectric material toward the substrate on which the first electrode layer is formed. be able to. Therefore, it is possible to manufacture a highly reliable inorganic electroluminescent element. In addition, since it is possible not to use a high-temperature process when forming the insulating layer, it is possible to use inexpensive glass, plastic, film, etc. as the substrate material in accordance with the manufacturing process of other components employed. it can. Therefore, it is possible to reduce the manufacturing cost of the inorganic EL element.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings. The same constituent elements are denoted by the same reference numerals, and the description thereof is omitted. In the present application, a thin film refers to a film having a thickness of less than 1 μm, usually a thickness of about several hundred nm. The thick film means a film having a thickness of 1 μm or more, usually about several μm to several tens of μm.

  FIG. 1 is a partial cross-sectional perspective view showing the structure of an inorganic EL element according to an embodiment of the present invention. The inorganic EL element includes a substrate 1, a first electrode 2 and a second electrode 6, a first insulating layer 3, a light emitting layer 4, and a second insulating layer 5 that are sequentially stacked between these electrodes. Is included.

In the present embodiment, the substrate 1 is made of alumina. In addition, as the material of the substrate 1, forsterite (2MgO · _SiO 2), steatite (MgO · _SiO 2), mullite _{(3Al 2 O 3 · 2SiO 2} ), beryllia (BeO), aluminum nitride (AlN) Ceramics including silicon nitride (Si ₃ N ₄ ), silicon carbide (SiC + BeO), zirconia (ZrO ₂ ), Macor (registered trademark), Photoval (registered trademark), and macerite (registered trademark) can be used. Or acrylic, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polycarbonate (PC), polyethersulfone (PES), polyarylate (PAR), polycyclic olefin (PCO, polynorbornene), polyimide (PI) A plastic substrate or film such as glass or glass may be used.

  These substrate materials are preferably used according to the manufacturing process and application. For example, when the light emitting layer 4 to be described later is formed by vapor deposition, heat treatment is required, and thus a heat resistant material such as a glass substrate is used. Alternatively, in the case where a binder coating film in which phosphor particles are dispersed or a phosphor film formed by a hydrothermal method is used as the light emitting layer 4, a plastic substrate or a film is used because a high temperature process becomes unnecessary. You can also. Regarding the use of plastic as the substrate and hydrothermal method, JP Bender, JF Wagner, S. Park, BL Clark, DA Keszler, “Inorganic” Inorganic Phosphor and ACTFEL Devices on Flexible Plastic Substrates ", 2002, Gent (Belgium) International Conference on Science and Technology of Luminescent Displays and Lighting Emissive Displays and Lighting).

  Further, the substrate material may be transparent or not, and even if it is a white reflective film or a black film, it can be used according to the application. For example, when the emitted light is extracted from the substrate side, a transparent substrate and a transparent electrode may be used, and when the emitted light is extracted from the opposite side of the substrate, a substrate having a high reflectance is used. The extraction efficiency can be increased.

  Both the first electrode 2 and the second electrode 6 have a predetermined pattern for constituting a matrix circuit. The first electrode 2 is made of platinum (Pt) and has a thickness of 200 nm, for example. The second electrode 6 is a transparent electrode made of indium tin oxide (ITO) and has a thickness of 200 nm, for example.

As a material for forming the first electrode 2, in addition to the above platinum, metals including gold (Au), iridium (Ir), palladium (Pd), silver (Ag), nickel (Ni), and alloys thereof Is used. Further, as the transparent electrode for forming the second electrode 6, in addition to the above ITO, indium zinc oxide (IZO), strontium ruthenate (SrRuO ₂ ), or the like may be used. Further, a metal mesh electrode or a combination of a metal mesh electrode and a transparent conductive film may be used.
In addition, when using a transparent substrate as the board | substrate 1, it is desirable to make the 1st electrode 2 into a transparent electrode. In that case, a metal or alloy electrode may be used for the second electrode 6.

  The first insulating layer 3 and the second insulating layer 5 are formed of a dielectric material (dielectric material). The first insulating layer 3 is a thick film having a thickness of 40 μm, for example. In the present embodiment, the first insulating layer 3 is made of PZT (Pb (lead) zirconate titanate). The second insulating layer 5 is a thin film having a thickness of 200 nm, for example. In the present embodiment, the second insulating layer 5 is formed of silicon nitride (SiNx). The second insulating layer 5 can be omitted depending on the voltage applied when the inorganic EL element is used. Conversely, the second insulating layer 5 may be a thick film.

PZT-based material _is one that the _{(Pb 1-X M X)} (Zr 1-Y Ti Y) substances having _{O 3} having a composition, an impurity was added with MeO a composition. Here, M includes strontium (Sr), barium (Ba), calcium (Ca), magnesium (Mg), and lanthanum (La), and 0 ≦ X ≦ 1.0 and 0 ≦ Y ≦ 1.0. It is. Me includes tantalum (Ta), niobium (Nb), tungsten (W), molybdenum (Mo), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni). , Zinc (Zn), yttrium (Y), bismuth (Bi), antimony (Sb), samarium (Sm), neodymium (Nd), silicon (Si), germanium (Ge), and boron (B).

Alternatively, a barium titanate-based material may be used as a dielectric material for forming the first insulating layer 3. The barium titanate-based material is obtained by adding an impurity having a composition of MeO to a substance having a composition of (Ba _1-X M _X ) (Ti _1-Y Me _Y ) O ₃ . Here, M includes strontium (Sr), calcium (Ca), magnesium (Mg), and lead (Pb), and 0 ≦ X ≦ 1.0 and 0 ≦ Y ≦ 1.0. Me includes zinc (Zn), niobium (Nb), tungsten (W), cobalt (Co), nickel (Ni), zirconium (Zr), molybdenum (Mo), chromium (Cr), manganese (Mn). , Iron (Fe), yttrium (Y), bismuth (Bi), antimony (Sb), tantalum (Ta), samarium (Sm), neodymium (Nd), silicon (Si), lithium (Li), holmium (Ho) , Boron (B).

Further, the first insulating layer 3 is made of alumina (Al ₂ O ₃ ), tantalum oxide (Ta ₂ O ₅ ), yttrium oxide (Y ₂ O ₃ ), aluminum oxynitride-titanium (AlON-TiON), or silicon nitride-based. compound _{(Si 3 N 4, SiN X} : Ta, SiN X: Ta, Zr) or the like may be formed by using a. These PZT materials, barium titanate materials, alumina, and other materials may be used not only for the first insulating layer 3 but also for the second insulating layer 5.

The light emitting layer 4 is made of a material exhibiting electroluminescence. The light emitting layer 4 is a manganese-activated zinc sulfide (ZnS: Mn) phosphor thin film, and has a thickness of 600 nm, for example. Other materials for the light emitting layer 4 include thulium-activated zinc sulfide (ZnS: Tm), terbium-activated zinc sulfide (ZnS: Tb), cerium-activated strontium sulfide (SrS: Ce), and europium-activated sulfide. Calcium (CaS: Eu), Cerium activated calcium sulfide (CaS: Ce), Eurobium activated barium thioaluminate (BaAl ₂ S ₄ : Eu), Eurobium activated barium magnesium thioaluminate ((Ba, Mg) Al ₂ S ₄ : Eu), sulfur containing sulfurium-activated strontium thiogallate (SrGa ₂ S ₄ : Eu), europium-activated calcium thioaluminate (CaAl ₂ S ₄ : Eu), copper-activated strontium sulfide (SrS: Cu) objects phosphor or europium activated magnesium gallate (MgGa _{2 4:} Eu), manganese activated yttrium oxide _{(Y 2 O 3: Mn)} , manganese activated yttrium oxide - gadolinium _{(Y 2 O 3 -Gd 2 O} 3: Mn) phosphor or the like can be used.

  In the dispersion type EL element, a phosphor such as copper-activated zinc sulfide (ZnS: Cu) or copper-manganese activated zinc sulfide (ZnS: Cu, Mn) can be used. Furthermore, in the dispersion type EL element using the multilayer structure particle disclosed in Patent Document 1, the same phosphor and insulator (dielectric material) as those used in the thin film type EL element are layered inside. Contained particles can be used.

Next, a method for manufacturing an inorganic EL element according to an embodiment of the present invention will be described. In this embodiment, the case where a thin film type inorganic EL element is manufactured will be described.
In the inorganic EL element according to the present embodiment, the first and second insulating layers 5 are desirably dense films in order to maintain high insulating performance in the inorganic EL element. Therefore, at least the first insulating layer 3 and preferably the second insulating layer 5 are also formed by spray deposition.

  The spray deposition method is a film deposition method in which powder of a material is ejected toward a substrate or the like on which film formation is performed and the powder is deposited by colliding with the substrate or the like at high speed. The jet deposition method has the following characteristics. That is, (1) a uniform film can be obtained from a material mixed with multiple elements. (2) A pattern can be formed without using a mask. (3) The film can be formed at high speed. (4) A low-temperature film can be formed, and the formed film has high strength and a high degree of adhesion to a substrate and is dense.

  The jet deposition method is also called a gas deposition method or an aerosol deposition method. For details, refer to Japanese Patent No. 3084286, and “Glass Deposition of Ultrafine Particles” (vacuum, 1992, 35, 7, p. 649-653).

  FIG. 2 is a schematic view showing a part of a film forming apparatus using a jet deposition method. The film forming apparatus includes a container 10, a gas introduction pipe 12, a transfer pipe 13, a nozzle 14, and a movable stage 15. The container 10 is a container for disposing the material powder 11. In the spray deposition method, fine particles of submicron order are used as the material powder 11.

The gas introduction pipe 12 supplies a gas (carrier gas) for conveying the powder 11 of the material. The gas introduction pipe 12 is arranged so that the tip thereof is buried in the powder 11 of the material. In this embodiment, nitrogen (N ₂ ) is used as the carrier gas, but in addition, inert gas including argon gas and helium gas, dry air, oxygen gas, hydrogen gas, and the like can be used. .

The transport pipe 13 sucks the material powder together with the gas and transports it to the nozzle 14.
The nozzle 14 injects the powder of the material conveyed by the conveyance pipe 13 toward the substrate. As the nozzle 14, it is desirable to use a high-speed nozzle capable of accelerating the fluid so that the speed of the powder of the material becomes about 50 m / s to 450 m / s when colliding with the substrate. Further, the shape of the emission end of the nozzle is prepared according to the pattern of film formation. Thereby, a desired pattern is formed with high accuracy.

  The movable stage 15 is a three-dimensionally movable stage for controlling the relative position between the nozzle 14 and the placed substrate 1. A desired pattern 20 is formed on the substrate 1 by spraying powder from the nozzle 14 while moving the movable stage 15. In the present embodiment, the nozzle 14 is fixed and the movable stage 15 is moved. Conversely, the stage may be fixed and the nozzle side may be moved. Alternatively, both the nozzle and the stage may be movable and their relative positions may be changed. The nozzle 14 and the movable stage 15 are used by being disposed in a film formation chamber in which the atmosphere is adjusted.

  In FIG. 2, when a carrier gas is introduced from a gas introduction pipe 12 into a container 10 in which a material powder 11 is arranged, the material powder 11 is blown up and floats in the carrier gas. The carrier gas in which the powder 11 of this material is suspended is supplied to the nozzle 14 through the transport pipe 13 and is jetted from the nozzle 14 toward the substrate 1. Thereby, the ultrafine particles accelerated at high speed collide with the substrate, and adhere to the substrate or the previously deposited deposit by the collision energy at that time.

According to such a jet deposition method, it is possible to form a thick film of about 1 μm to several tens of μm. In such a thick film, at least the average crystal grain size is 1 μm or less and the film density is 70% or more. Desirably, a dielectric thick film having an average crystal grain size of 100 nm or less and a film density of 90% or more, more desirably, an average crystal grain size of 50 nm or less and a film density of 95% or more. A dielectric thick film can be produced.
Further, since the fine particles ejected from the nozzle are deposited on the substrate or the like by the collision energy, it is not necessary to heat the substrate or the like, and it is possible to form the film in a normal temperature atmosphere.

FIG. 3 is a flowchart showing a method for manufacturing an inorganic EL element according to this embodiment.
In step S <b> 1, the first electrode 2 is formed on the substrate 1. That is, first, a Pt electrode layer having a thickness of 200 nm is formed on a substrate 1 such as alumina by sputtering, and then a pattern is formed by using a photolithography method and a dry etching method for the Pt electrode layer.

Next, in step S2, the first insulating layer 3 is formed on the substrate 1 on which the first electrode 2 is formed. That is, as shown in FIG. 2, a carrier gas such as N _{2 is} introduced from a gas introduction pipe 12 into a container 10 in which PZT powder is arranged, and the powder of the material suspended thereby is transferred to a conveyance pipe 13. And ejected from the nozzle 14 toward the substrate 1. Such film formation is performed in a room temperature film formation chamber.

  Here, as the material powder 11, a material prepared in advance may be used, or an ultrafine particle generation chamber is connected to the container 10, and the generated powder is directly supplied to the container 10. Anyway. The material powder 11 can be produced, for example, by producing an organometallic hydrate by a known alkoxide method and thermally decomposing it. Here, the average particle diameter of the material powder 11 is desirably about 0.1 μm to 5 μm. For example, such powder can be produced by using the alkoxide method.

  Further, the substrate 1 on which the PZT thick film is formed by spray deposition is baked. The firing temperature is desirably lower than the melting point or softening point of the substrate 1, and in this embodiment, the firing is performed in an oxygen atmosphere at 600 ° C. for about 10 minutes. Thereby, the crystallinity of the PZT thick film is improved and the filling rate of the material of the electrode layer and the thick film layer is improved, so that the physical characteristics in each layer are stabilized.

Next, in step S3, a ZnS: Mn thin film to be the light emitting layer 4 is formed on the first insulating layer 3 by an electron beam (EB) evaporation method.
Next, in step S4, a SiNx thin film to be a second insulating layer is formed on the light emitting layer 4 by sputtering.
Next, in step S5, the second electrode 6 is formed. The second electrode 6 is formed by first forming an ITO transparent electrode layer on the second insulating layer by a sputtering method, and then etching the ITO electrode layer by using a photolithography method and a dry etching method. The pattern is formed.

The performance of the thus formed inorganic EL element was evaluated.
For the first insulating layer 3 (PZT thick film), the following values were obtained.
Dielectric constant: 1000-1500
Dielectric strength: 0.7MV / cm
Performance index (ε · Ebd value): 60 to 90 μC / cm ²
This figure of merit ε · Ebd value greatly exceeds the value (10 to 30 μC / cm ² ) in the PZT thick film formed by the green sheet method, and it can be said that it has a very good insulation performance.

Further, when a wiring is drawn out from the first electrode 2 and the second electrode 6 of this inorganic EL element, and an electric field having a frequency of 1 KHz and a pulse width of 50 μs is applied between these electrodes, an emission luminance of about 600 cd / m ² is obtained. It was obtained with good reproducibility. At that time, even when a voltage of up to 300 V was applied, there was no dielectric breakdown and high stability could be obtained.

  In the present embodiment described above, only the thick PZT film used as the first insulating layer is formed by spray deposition. However, other layers may also be formed by spray deposition.

For example, when the first electrode 2 is formed by the jet deposition method, the metal is heated and evaporated by the resistance heating method, and collides with atoms of the carrier gas to generate metal fine particles. As shown in FIG. 2, the fine metal particles are supplied together with a carrier gas to the nozzle 14 via the transfer tube 13 and are sprayed toward the substrate. At that time, a desired electrode pattern may be formed by controlling the movable stage 15 and relatively changing the positions of the substrate 1 and the nozzle 14. As described above, according to the jet deposition method, since drawing can be performed directly on the substrate 1 using the nozzle 14, complicated processes such as pattern formation using a mask can be omitted, and the manufacturing process can be simplified. .
Note that when the metal fine particles are generated, the metal material may be heated using an induction heating method, an arc heating method, an induction plasma heating method, a laser heating method, or the like.

  Similarly, the light emitting layer 4, the second insulating layer 5, and the second electrode 6 can also be formed by a jet deposition method. Since the jet deposition method does not include a process that raises the powder of the material to a high temperature or causes a chemical change, any of metal, glass, ceramics, and plastic can be used as the powder of the material. is there.

FIG. 4 shows a modification of the method for manufacturing an inorganic EL element according to this embodiment. In this modification, a plurality of layers included in the inorganic EL element are formed by a jet deposition method.
In FIG. 4, a nozzle 14 a that ejects Pt that is the material of the first electrode 2, a nozzle 14 b that ejects PZT that is the material of the first insulating layer 3, and ZnS: Mn that is the material of the light emitting layer 4 are ejected. The nozzles 14c are arranged at a predetermined interval in the stacking order. As shown in FIG. 4, while the substrate 1 is moved in the arrangement direction of the nozzles 14a to 14c, the powders of the material are ejected from the nozzles 14a to 14c at predetermined time intervals, thereby sequentially laminating. As a result, the first electrode 2, the first insulating layer 3, and the light emitting layer 4 are sequentially formed on the substrate 1. The film formation pattern and the film thickness can be adjusted by controlling the shape of the emission end of the nozzle, the moving speed of the nozzle or the substrate, the conveying condition of the powder of the material supplied to the nozzle, and the like.

  In this modification, the first electrode 2, the first insulating layer 3, and the light emitting layer 4 are formed by spray deposition. However, by providing a nozzle, all layers are formed by spray deposition. You may do it. Thus, by forming the plurality of layers included in the inorganic EL element by the jet deposition method, the manufacturing process can be simplified and a large-scale facility is not required.

  As described above, when a film is formed by the jet deposition method, a thick film of about 1 μm to several tens of μm can be formed at high speed. Therefore, the manufacturing process of the inorganic EL element can be simplified. Moreover, the process in high temperature (for example, 900 degreeC) for densifying a film | membrane is also unnecessary. Therefore, it is possible to form a dense and smooth film in which generation of pores, cracking due to thermal reaction or thermal stress between layers is suppressed. Further, interdiffusion or the like at the interface between the electrode and the insulating layer or at the interface between the insulating layer and the light emitting layer is reduced.

Since the thick film formed by this spray deposition method is desirably a dense film having a film density of 95% or more, a flattening process such as polishing is facilitated.
Furthermore, since such a thick film has high withstand voltage, the reliability of the inorganic EL element can be improved. In addition, the thick film formed by the jet deposition method can achieve the same breakdown voltage with a smaller film thickness as compared with a film formed by conventional screen printing or the like. That is, when the drive voltage is the same, the voltage applied to the light emitting layer increases, and the luminance of the inorganic EL element increases.

  In addition, since film formation can be performed at room temperature, a material having relatively low heat resistance can be used as a substrate material, and the range of material selection can be widened. For example, in addition to the alumina used in the present embodiment, metals, ceramics, glass, plastics and the like can be used. In particular, by using a transparent substrate such as glass or plastic, a transparent color display can be realized.

  In the above embodiment, the case of manufacturing a thin-film inorganic EL element has been described. However, in the case of manufacturing a dispersed EL element, a known method such as applying a binder in which a phosphor is dispersed or printing is known. The light emitting layer can be formed using the method. Even in that case, the withstand voltage of the insulating layer can be increased by forming the insulating layer by spray deposition. Therefore, it is possible to obtain the same effect as the above-described thin film type inorganic EL element, and it is possible to improve the reliability of the dispersion type inorganic EL element.

  The present invention can be used in inorganic electroluminescent elements used in flat display devices, surface light sources and the like.

It is a partial cross section perspective view which shows the structure of the inorganic electroluminescent element which concerns on one Embodiment of this invention. It is a schematic diagram which shows a part of film-forming apparatus by a jet deposition method. It is a flowchart which shows the manufacturing method of the inorganic electroluminescent element which concerns on one Embodiment of this invention. It is a figure for demonstrating the modification of the manufacturing method of the inorganic electroluminescent element which concerns on one Embodiment of this invention. It is sectional drawing which shows the structure of the conventional inorganic electroluminescent element. It is sectional drawing which shows the conventional inorganic electroluminescent element.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Substrate 2,22,32 1st electrode 3,23,33 1st insulating layer 4,24,34 Light emitting layer 5,25,35 2nd insulating layer 6,26,36 2nd electrode 10 Container 11 Raw material powder 12 gas introduction pipe 13 transport pipe 14 nozzle 15 movable stage 20 pattern 21 glass substrate 22 transparent first electrode 23 thin film first insulating layer

Claims (15)

Forming a first electrode layer having a predetermined pattern on the substrate (a);
Wherein toward the first substrate on which the electrode layer is formed, the average particle diameter is the 0.1μm~5μm a powder material having a dielectric, and ejected from the nozzle by the aerosol deposition method, the rate A step of forming a first insulating layer having an average crystal grain size of 100 nm or less and a film density of 90% or more by colliding with and depositing on the first electrode layer at 50 m / s to 450 m / s. (B) and
A step (c) of forming a light emitting layer on the first insulating layer using particles exhibiting electroluminescence or a precursor thereof;
Forming a second electrode layer on the light emitting layer (d);
The manufacturing method of the inorganic electroluminescent element which comprises this. The step (a) includes forming a predetermined pattern by spraying a conductive material powder from the nozzle using the aerosol deposition method toward the substrate. Item 2. A method for producing an inorganic electroluminescent element according to Item 1. The step (c) includes depositing a powder of a material exhibiting electroluminescence toward the first insulating layer by spraying from a nozzle using an aerosol deposition method. The manufacturing method of the inorganic electroluminescent element of description.   The method of manufacturing an electroluminescent element according to claim 1, wherein the step (c) includes forming the light emitting layer using a binder in which a powder of a material exhibiting electroluminescence is dispersed. After the step (c), the method further includes a step (c ′) of forming a second insulating layer on the light emitting layer,
Step (d) includes forming the second electrode layer on the second insulating layer,
The manufacturing method of the inorganic electroluminescent element of any one of Claims 1-4. The inorganic electroluminescence according to claim 5, wherein step (c ′) includes depositing a powder of a dielectric material toward the light emitting layer by spraying from a nozzle using an aerosol deposition method. Sense element manufacturing method. In step (d), a powder of a conductive material is deposited from a nozzle using an aerosol deposition method toward the light emitting layer or the second insulating layer, thereby depositing a predetermined pattern. The manufacturing method of the inorganic electroluminescent element of any one of Claims 1-6 including forming. A plurality of nozzles for respectively injecting powders of materials constituting the plurality of layers are arranged in the stacking order of the plurality of layers included in the stacked structure, and the positions of the plurality of nozzles and the substrate are relatively while changing the, by sequentially injecting the powder material toward the base plate from the plurality of nozzles by the aerosol deposition method to form a laminated structure on the substrate, according to claim 1 to 7 The manufacturing method of the inorganic electroluminescent element of any one of Claims 1. When the average particle diameter of the powder of the material sprayed from the nozzle is 0.1 μm to 5 μm, and the powder of the material sprayed from the nozzle collides with the substrate or a layer formed on the substrate The manufacturing method of the inorganic electroluminescent element of any one of Claim 2, 3 , 6-8 whose speed | velocity | rate of this powder is 50m / s-450m / s. Forming a first electrode layer having a predetermined pattern on the substrate (a);
A step (b) of forming a first insulating layer by spraying and depositing a powder of a dielectric material from a nozzle toward the substrate on which the first electrode layer is formed;
A step (c) of forming a light emitting layer on the first insulating layer using particles exhibiting electroluminescence or a precursor thereof;
Forming a second electrode layer on the light emitting layer (d);
Comprising a, a first electrode layer formed before SL on the substrate, depositing by injecting the powder material from the nozzle is carried out at room temperature, method for producing a non-machine electroluminescent element. The layer formed on the substrate or on the substrate, after the step of Ru is deposited by spraying the powder material from the nozzle, further comprising the step of performing sintering for controlling the crystallinity of the deposited material The manufacturing method of the inorganic electroluminescent element of any one of Claims 1-10.   The manufacturing method of the inorganic luminescent element of Claim 11 whose baking temperature at the time of performing the said baking is below the melting | fusing point or softening point of the said board | substrate. A substrate,
A first electrode layer formed on the substrate;
It is a thick film having a dielectric property, and is formed by spraying and depositing a powder of a dielectric material on the substrate on which the first electrode layer is formed using an aerosol deposition method , A first insulating layer having an average crystal grain size of 100 nm or less and a film density of 90% or more ;
A light emitting layer exhibiting electroluminescence formed on the first insulating layer;
A second electrode layer formed on the light emitting layer;
An inorganic electroluminescent device comprising: A thick film having a dielectric property formed between the light emitting layer and the second electrode layer, the powder of the dielectric material being directed toward the light emitting layer, using an aerosol deposition method The inorganic electroluminescent device according to claim 13, further comprising a second insulating layer formed by spraying and depositing, having an average crystal grain size of 100 nm or less and a film density of 90% or more . The inorganic electroluminescent element according to claim 13 or 14 , wherein the first or second insulating layer has an average crystal grain size of 50 nm or less and a film density of 95% or more.

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