JP2006278021A - Inspection method and structure of organic function element sealing film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inspection method of a sealing film of an organic function element with a high shielding property against oxygen and moisture and with characteristics hardly degraded. <P>SOLUTION: The inspection method of the sealing film covering the organic function element includes a metal film-forming process of forming a metal film over a sealing film after a sealing process of forming a sealing film on the organic function element to cover it, a positive electrode oxidizing process of forming a positive electrode oxidizing metal film by carrying out positive electrode oxidization by having a metal film in contact with a forming liquid with the metal film as a positive electrode, and an inspection process of inspecting electric characteristics of the sealing film and the organic function element covered with the positive electrode oxidizing metal film. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method and a structure for inspecting a sealing film of an organic functional element using phenomena such as charge generation, movement, photoconduction, or electroluminescence due to charge recombination in an organic compound material.

  Organic functional elements such as organic electroluminescence (EL) display elements have been put into practical use, and the field of organic electronics-photonics such as organic transistors, organic FETs, and organic solar cells is expanding. Organic functional elements using organic high-molecular materials or organic low-molecular materials such as organic semiconductors and conductive polymers can realize a large area, lightweight and flexible low power consumption device, which is difficult with inorganic semiconductor elements. Low-temperature processes in manufacturing, energy saving and cost reduction are also expected.

  For example, an organic EL element basically has an organic functional layer (one or more thin films including a light emitting layer made of an organic compound material exhibiting electroluminescence that emits light by current injection) sandwiched between an anode and a cathode. The excitons formed when electrons and holes injected from the electrode are recombined return from the excited state to the ground state to generate light. For example, an organic EL element is configured by sequentially laminating a transparent electrode of an anode, an organic functional layer, and a metal electrode of a cathode on a transparent substrate, and obtains light emission from the transparent substrate side. The organic functional layer is a single layer of a light emitting layer, or a three-layer structure of an organic hole transport layer, a light emitting layer and an organic electron transport layer, or a two layer structure of an organic hole transport layer and a light emitting layer, and appropriate layers between them. Is a laminate in which an electron or hole injection layer or a carrier block layer is inserted.

  As an organic EL display panel (a display panel in which one or more organic EL elements are formed on a substrate), for example, a matrix display type or a panel having a predetermined light emission pattern is known.

  When this organic EL element is exposed to the atmosphere, it tends to deteriorate due to the influence of gases such as moisture and oxygen, and other molecules in the environment of use. In particular, the interface between the electrode of the organic EL element and the organic functional layer However, the characteristic deterioration is remarkable, and there is a problem that the light emission characteristics such as luminance and color are lowered. In order to prevent this, a method of sealing the organic EL element with an inorganic single layer protective film such as silicon oxide in an organic EL display panel to suppress the deterioration can be considered. If there is a pinhole, moisture, oxygen, or the like enters from the portion, and a portion where the organic EL element does not emit light, a so-called dark spot, is enlarged.

  Therefore, sealing with nitrides such as silicon nitride is currently under study as organic EL element thin film sealing. However, pinholes are always easily generated in a protective film formed by sputtering or plasma (CVD) chemical vapor deposition. Therefore, a multilayer protective film of a polymer film and an inorganic film is considered in the organic EL panel (see Patent Document 1).

  In any case, the biggest problem with organic functional elements sealed with thin films is that pinholes are small and cannot be found at the beginning, and moisture and oxygen gradually enter the pinholes after shipment. This damages the organic functional element and enlarges the part that does not function.

In other words, in order to check the quality of organic functional elements, the electrical characteristics are measured, and the electrical characteristics are normal and judged to be non-defective, but time has passed since the quality test due to thermal stress after product shipment. After that, there is a problem that the device becomes defective due to pinhole expansion or the like. For example, when mass production of an organic EL display panel or the like is performed, it is very difficult to inspect all the small pinholes of the plurality of organic functional elements.
JP2003-282241A.

  Therefore, the present invention provides an example of a method and a structure for inspecting a sealing film of an organic functional element that has a high shielding property against oxygen and moisture with respect to the organic functional element and that hardly deteriorates the characteristics of the organic functional element.

The organic functional element sealing film inspection method according to claim 1 is an inspection method of a sealing film covering the organic functional element,
A metal film forming step of forming a metal film over the sealing film after the sealing step of forming a sealing film covering the organic functional element;
An anodic oxidation step in which the metal film is brought into contact with a chemical conversion solution and anodized using the metal film as an anode to form an anodized metal film;
An inspection step of inspecting electrical characteristics of the organic functional element covered with the sealing film and the anodized metal film.

The organic functional element sealing film structure according to claim 6 is a structure of a sealing film covering the organic functional element,
A sealing film covering the organic functional element, and an anodized metal film formed by anodizing the metal film laminated on the sealing film as an anode are included.

BEST MODE FOR CARRYING OUT THE INVENTION

  An organic EL display panel will be described below with reference to the drawings as an example of an embodiment of the present invention.

  As shown in FIG. 1, the organic functional element sealing film structure is formed on a sealing film 16 including an inorganic film such as silicon nitride covering a plurality of organic EL elements D on the substrate 10 of the organic EL display panel. As shown in FIG. 2, a metal film MF such as Ta or Ta is formed, and thereafter, the metal film MF is anodized to produce an anodized metal film OM including an oxide film Ox.

  Since the anodizing process is a wet process, if there is a pinhole in the sealing film 16 of the organic EL display panel, the presence or absence of black spots can be determined when the panel is turned on after the anodizing process. it can.

  As a procedure of the organic functional element sealing film inspection method, as shown in FIG. 3, a step S1 for producing a plurality of organic EL elements on a substrate and a sealing film covering the organic functional elements on the substrate with silicon nitride or the like are provided. A sealing step S2 to be formed, a metal film forming step S3 for forming a metal film such as Al, Ta, Ti or the like on the sealing film by a film forming method such as a vapor deposition method or a sputtering method, and a metal film Anodizing step S4 in which a substrate coated with is immersed in a predetermined chemical conversion solution and a current is supplied from a power source between a counter electrode (cathode) and a metal film (anode) to form an anodized metal film, and anodization is performed. A cleaning step S5 for washing the substrate coated with the metal film, and an inspection step S6 for inspecting their electrical characteristics (light emission state) by energizing the organic functional elements covered with the sealing film and the anodized metal film. And are executed sequentially.

  Specific cleaning and inspection of the organic EL display panel will be described.

<Organic EL device>
First, as shown in FIG. 4, a first display electrode 13 made of, for example, indium tin oxide (ITO) is formed on the substrate 10 by vapor deposition or sputtering. Thereafter, a predetermined pattern such as a stripe is formed by a photolithography process. As the transparent electrode material, indium zinc oxide, ZnO, and SnO are also used.

On the first display electrode 13, for example, a hole injection layer made of copper phthalocyanine, a hole transport layer made of TPD (triphenylamine derivative), a light emitting layer made of Alq3 (aluminum chelate complex), Li ₂ O (lithium oxide) ) Are sequentially deposited to form the organic functional layer 14. In addition, the material of the organic functional layer can be selected and appropriately stacked to form red R, green G, and blue B light emitting portions.

  Further, a predetermined pattern such as a stripe is formed on the organic functional layer 14 by vapor deposition or sputtering so that the second display electrode 15 made of, for example, Al is orthogonally opposed to the electrode pattern of the transparent electrode 13 via the organic functional layer 14. The film is formed.

  As described above, each of the organic EL elements of the panel is sequentially laminated on the substrate 10 and includes one or more organic functional layers 14 including the first display electrode 13 (anode of the transparent electrode) and the light emitting layer made of an organic compound. And a second display electrode 15 (a cathode of a metal electrode). As a material for the substrate 10, an organic material such as a polymer compound can be used in addition to an inorganic material such as glass.

  In the case where the substrate 10 is made of synthetic resin, it is also possible to use a substrate whose surface is covered with a substrate-side inorganic film made of an inorganic material such as silicon nitride or silicon nitride oxide. As the plastic substrate, films of polyethylene terephthalate, polyethylene-2,6-naphthalate, polycarbonate, polysulfone, polyethersulfone, polyetheretherketone, polyphenoxyether, polyarylate, fluororesin, polypropylene and the like can be applied.

<Sealing film>
Next, as shown in FIG. 5, the organic EL element is formed with a single layer of an insulating sealing film 16 such as a silicon nitride film so as to cover the back surface of the second display electrode 15. The sealing film includes an inorganic film, and the inorganic film is made of a nitride such as silicon nitride, a nitrided oxide such as silicon nitride oxide, an oxide such as silicon oxide or aluminum oxide, or a carbide such as silicon carbide. .

  In addition to plasma CVD, for example, a catalytic chemical vapor deposition method can be used to form the inorganic sealing film 16. The catalytic chemical vapor deposition method is a method in which a thin film molecule is generated from a raw material using a high-temperature catalyst and deposited on a substrate. Although the catalyst itself is 1000 ° C. or higher, the thin film carried on the cooling holder can be suppressed to 100 ° C. or lower, so that the organic EL element is not damaged.

  The sealing film 16 may be a multi-layer sealing of a polymer and an inorganic film in addition to a single-layer sealing only of an inorganic film. For example, as shown in FIG. 6, the sealing film 16 may be formed of two layers of a polymer film 16P of polyurea or polyimide film by vapor deposition polymerization and an inorganic film 16S of silicon nitride film. The edge of the polymer film 16P is preferably formed so that the film thickness gradually decreases. This is to ensure smooth deposition of the inorganic film 16S. The inorganic film 16S is preferably formed so as to cover the edge of the polymer film 16P.

  In the vapor deposition polymerization method for forming the polymer film 16P, two or more kinds of organic molecules are evaporated and vaporized inside the vacuum chamber, and the generated gas is contacted with, reacted with, and deposited on a predetermined coating surface to polymerize the organic molecules. That is, a film forming method in which a polymer thin film is produced by polymerizing a monomer in a vacuum. According to vapor deposition polymerization, a polymer chemical film can be obtained if the monomer or oligomer has a vapor pressure. Polyimide is a polymer having a molecular structure such as a thermally and chemically stable imide ring (heterocycle) or aromatic ring in the main chain, and has excellent heat resistance, mechanical strength, electrical insulation, and chemical resistance. Yes. As the polymer film, polyurea or polyimide is preferable. The polyimide film is formed by condensation polymerization of pyromellitic dianhydride and a diamine monomer. Examples of the raw material for the polyurea film include MDI (4,4 ′ diphenylmethane diisocyanate) and ODA (4,4 ′ diamine phenyl ether).

  As shown in FIG. 7, in another embodiment, the organic EL element D may be further protected by a multilayer sealing film 16m. The organic EL element D sequentially covers a first inorganic film 16S1, a first polymer film 16P1, a second inorganic film 16S2, and a second polymer film 16P2 so as to cover the back surface of the second display electrode 15. , A third inorganic film 16S3, and a third polymer film 16P3. In this way, in the case of a further multilayer sealing film 16m structure in which a polymer film and an inorganic film are alternately laminated, each layer is formed by repeating the film formation process of the polymer film and the inorganic film. As described above, in any of the embodiments, the inner polymer film is covered and embedded in a pair of inorganic films including the edge thereof. Further, the side of the multilayer sealing film 16m that contacts the metal film may be the third polymer film 16P3 or the fourth inorganic film 16S4 (shown by a broken line in FIG. 7).

<Metal film>
Next, as shown in FIG. 8, a metal film MF having a predetermined thickness is deposited on the surface of the sealing film 16 of the substrate 10 with a predetermined film thickness, such as Al, Ti, or Ta, by using a sputtering method or a vapor deposition method. Deposit. At this time, the metal film is not attached to portions that should not be short-circuited, such as the end portions of the first and second display electrodes.

<Anodic oxidation>
Next, as shown in FIG. 9, for example, the substrate 10 on which an Al metal film MF is deposited is immersed in the chemical conversion liquid 22 in the electrolytic cell 21 so as to face the counter electrode 23. Anodization of the metal film MF is performed by applying a positive voltage to the metal film MF. At this time, a mask is formed on a portion where the substrate 10 should not be anodized, such as the end portions of the first and second display electrodes.

The surface of the metal film MF on the substrate 10 is converted into an Al ₂ O ₃ oxide film Ox by anodization, and an anodized metal film OM composed of a lower metal film MF and an upper oxide film Ox is formed. . In this way, a substrate whose surface of the sealing film 16 is covered with the anodized metal film OM is obtained.

  A scratch-preventing polymer hard coat layer can be provided as a second sealing film on the anodized metal film OM.

  As an anodizing solution for anodizing aluminum, there are tartaric acid and ethylene glycol electrolytes having a pH of 7.0 ± 0.5. Japanese Patent Laid-Open No. 2-85826 provides a detailed reference for the chemical conversion treatment of aluminum. The chemical conversion liquid, voltage, current, processing time, and the like are determined so that the porosity becomes small so that the oxide film Ox of the anodized metal film OM becomes dense.

  The film thickness for forming the pores of the oxide film Ox is controlled by the formation time. Even if the above method is used, the size of the pores can be controlled to a desired film thickness by controlling the chemical conversion liquid concentration, the current density, and the like. The porosity is expressed as a ratio of the volume of the portion where the voids by the pores are formed in the entire volume of the substrate surface layer portion, and the entire oxide film Ox including the pores with the total pore volume as V1. When the product is V2, it is expressed by V1 / V2.

  When electrolysis is performed in a specific solution using aluminum as an anode (anode), an oxide film is formed on the aluminum. When most metals, such as copper and zinc, are anodized, these metals only dissolve and a thick oxide film cannot be formed.

  Depending on the type of electrolytic bath for aluminum anodization, a barrier type oxide film and a porous type oxide film can be formed. When aluminum is anodized in a neutral aqueous solution of boric acid-sodium borate (pH 5-7) or an aqueous solution of ammonium tartrate, citric acid, maleic acid, glycolic acid or the like, a barrier type film is formed. Since these aqueous solutions have a weak ability to dissolve aluminum oxide, a dense thin oxide film can be formed on aluminum by anodic oxidation. The thickness of the barrier type oxide film depends on the voltage at the time of anodizing. If anodization is performed at a high voltage, a thick barrier type film can be formed. However, since dielectric breakdown occurs, the limit voltage is about 500V to 700V. Here, a barrier-type film is preferably used.

  When the bath temperature of the electrolytic bath is low, the growth rate of the oxide film is good and a hard oxide film is formed. An oxide film anodized in a sulfuric acid bath at around 0 ° C. is put into practical use as a hard oxide film. When the bath temperature of the electrolytic bath is a high temperature such as 60 to 75 ° C., the oxide film is thin and soft, and may be in an electropolished surface state.

  FIG. 10 is a partially enlarged rear view of an organic EL display panel including a plurality of organic EL elements after anodization. The organic EL display panel includes a plurality of organic EL elements arranged in a matrix on the substrate 10. A row electrode 13 (anode first display electrode) including a transparent electrode layer, an organic functional layer, and a column electrode 15 (second display electrode) including a metal electrode layer intersecting the row electrode are formed on the substrate 10. It is constructed by sequentially laminating. The row electrodes are each formed in a strip shape and are arranged so as to be parallel to each other at a predetermined interval, and the same applies to the column electrodes. Thus, the matrix display type display panel has an image display array composed of light emitting pixels of a plurality of organic EL elements formed at intersections of a plurality of row and column electrodes. A sealing film 16 is formed so as to cover the plurality of organic EL elements, and an anodized metal film OM is formed thereon.

<Inspection>
In the inspection of the organic functional element, a predetermined voltage is applied between the row electrode 13 and the column electrode 15 of the organic EL display panel, and the light emitting pixel and the electrical characteristics are measured. Since the anodic oxidation process is a wet process, if there is a pinhole in the sealing film 16 of the organic EL display panel, the energization inspection of the element indicates black spot expansion, and the organic functional element can be determined to be defective. Thereby, the quality of the panel can be determined.

  As described above, according to the present embodiment, since the anodizing process is a wet process, when there is a pinhole reaching the organic EL element in the sealing film made of silicon nitride or the like, an abnormality (black dot expansion) appears in the light emission state. It can be judged as a defective product.

  Although the embodiment of the organic EL element has been described above as the organic functional element, the organic functional element sealing film structure and the inspection method are also applied to an organic semiconductor device such as an organic transistor, an organic FET, and an organic solar cell as the organic functional element. it can.

  Furthermore, according to the organic functional element sealing film structure, an anodized oxide becomes an oxide, so that the barrier ability against moisture and oxygen is improved. Therefore, the barrier property is further improved by sealing with silicon nitride and an anodized metal film. At this time, the metal film may be configured as a sealing structure including only an oxide film oxidized in the entire film thickness direction, in addition to an oxide film in the upper part in the film thickness direction and a metal film in the lower part.

  Since anodic oxidation is an oxidation reaction, the film thickness becomes thicker due to oxidation than the metal film thickness. This effect can be seen both in the film thickness direction and in the lateral direction. Even if there is a pinhole in the metal film formed on the silicon nitride film, the pinhole is buried by the thickening of the film due to the anodizing treatment, and pinhole-free sealing is achieved. It becomes a test film.

  In the anodizing treatment, even if there is a pinhole reaching the organic EL element, if the cathode of the organic EL element is aluminum and an electric field is also applied to the cathode, the chemical solution reaching the cathode and the aluminum of the cathode It reacts and is oxidized to form aluminum oxide having a high barrier property, improving the sealing ability and preventing the expansion of black spots.

  Furthermore, since the sealing film has a multilayer structure in which an inorganic film and a polymer film are alternately laminated, the polymer film has a low barrier performance against moisture and oxygen, but pinholes that may exist in the inorganic film are removed from the polymer film. Since the film is embedded and flattened and an inorganic film is laminated, a sealing film having no defect can be formed.

  In the above-described embodiments, the vapor deposition polymerization method was used as a method for producing a polymer film such as polyureas, but the present invention is not limited to this, and UV curing resin coating, chemical vapor deposition (plasma polymerization method) Or a spraying method in a vacuum, so-called spraying method, can also be applied.

  Further, in the above-described embodiments, the simple matrix display type organic EL display panel has been described. However, the present invention can also be applied to an active matrix display type panel substrate using TFTs or the like.

The partial cutaway perspective view of the board | substrate in the organic EL display panel manufacturing process by this invention. The partial cutaway perspective view of the board | substrate in the organic EL display panel manufacturing process by this invention. The flowchart explaining the organic functional element sealing film test | inspection method by this invention. The fragmentary sectional view of the board | substrate in the organic EL display panel manufacturing process by this invention. The fragmentary sectional view of the board | substrate in the organic EL display panel manufacturing process by this invention. The fragmentary sectional view of the board | substrate in the organic electroluminescent display panel manufacturing process of other embodiment by this invention. The fragmentary sectional view of the board | substrate in the organic electroluminescent display panel manufacturing process of other embodiment by this invention. The fragmentary sectional view of the board | substrate in the organic EL display panel manufacturing process by this invention. Sectional drawing of the electrolytic cell explaining the anodizing process by this invention. The partial expanded rear view of the organic electroluminescence display panel of other embodiment by this invention.

Explanation of symbols

10 Substrate 13 First display electrode (anode of transparent electrode)
14 Organic functional layer (light emitting layer)
15 Second display electrode (cathode of metal electrode)
16 Sealing film 16P Polymer film 16S Inorganic film MF Metal film Ox Oxide film OM Anodized metal film 21 Electrolyzer 22 Chemical conversion liquid 23 Counter electrode

Claims (12)

A method for inspecting a sealing film covering an organic functional element,
A metal film forming step of forming a metal film over the sealing film after the sealing step of forming a sealing film covering the organic functional element on the organic functional element;
An anodic oxidation step in which the metal film is brought into contact with a chemical conversion solution and anodized using the metal film as an anode to form an anodized metal film;
An inspection step of inspecting electrical characteristics of the organic functional element covered with the sealing film and the anodized metal film, and an organic functional element sealing film inspection method.   The organic functional element sealing film inspection method according to claim 1, wherein the sealing film includes an inorganic film.   2. The organic functional element sealing film inspection method according to claim 1, wherein the sealing film is composed of a multilayer film of an inorganic film and a polymer film alternately stacked.   4. The organic functional element sealing film inspection method according to claim 2, wherein the inorganic film contains at least one of nitride, nitride oxide, oxide, and carbide.   The organic functional element sealing film inspection method according to claim 1, wherein the metal film contains Al, Ta, or Ti. A structure of a sealing film covering the organic functional element,
An organic functional element sealing film comprising: a sealing film covering the organic functional element; and an anodized metal film formed by anodizing a metal film laminated on the sealing film as an anode Construction.   The organic functional element sealing film structure according to claim 6, wherein the sealing film includes an inorganic film.   The organic functional element sealing film structure according to claim 6, wherein the sealing film is composed of a multilayer film of an inorganic film and a polymer film alternately stacked.   9. The organic functional element sealing film structure according to claim 7, wherein the inorganic film includes at least one of nitride, nitride oxide, oxide, and carbide.   The organic functional element sealing film structure according to claim 6, wherein the metal film contains Al, Ta, or Ti.   The organic functional element sealing film structure according to claim 6, wherein a second sealing film is provided on the anodized metal film.   The organic functional element sealing film structure according to claim 6, wherein the organic functional element is an organic EL element.

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