JP2002190389A - Method and device for manufacturing organic el element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and a device which will not degrade element performance by preventing the alteration of a material deposited at a part, capable of mixed with an evaporation source under mechanical shock, or the like, and moreover to facilitate refinement of a material recovered for reuse. SOLUTION: Related to an organic EL thin-film vapor deposition, where an organic EL material 3 in an evaporation source 2 is gasified and then deposited on a film-forming substrate 4 for forming a thin-film, components, such as a chamber 1, shutters 5 and 6, or the like, other than the film-forming substrate 4, where the organic material 3 is deposited are inactive materials a the such that the organic material 3 will not deteriorate, related to a device for vapor-depositing organic EL element. The organic EL element vapor- depositing method uses this device.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for manufacturing an organic EL device, and more particularly to a method for vaporizing an organic EL device material (also referred to as an organic EL material) in order to form an organic thin film for an organic EL device by a vacuum deposition method. The present invention relates to a method and an apparatus for manufacturing an organic EL device.

[0002]

2. Description of the Related Art A general structure of an organic EL device is as follows.
An organic thin film layer such as a hole transport layer, a light emitting layer, and an electron transport layer is formed between an anode and a cathode made of a transparent conductive film, and the positive electrode injected into the light emitting layer from the cathode via the hole transport layer is formed. Light emission occurs when the holes and the electrons injected from the cathode into the light emitting layer via the electron transport layer are recombined. At this time, a so-called dark spot is generated by co-evaporation of an impurity or an alteration in the material, which causes a problem that a non-colored portion appears in a display device.

As one of the methods for preparing an organic thin film for an organic EL device, there is a vacuum deposition method disclosed in Japanese Patent Application Laid-Open No. 2000-6805.
No. 5 publication. In vacuum evaporation, organic EL
A vapor deposition material vaporized from an evaporation source heated to a temperature equal to or higher than the vaporization temperature of the vapor deposition material is deposited as a solid on a deposition substrate to form a thin film. At this time, it is important to make the film thickness uniform, but generally, a method of stabilizing the amount of evaporation from the evaporation source and then depositing it on the substrate surface is used. for that reason,
An organic EL which is provided with a shutter at one or both of an evaporation source side and a substrate side in a vapor deposition apparatus to vaporize from the evaporation source
When the evaporation amount is stabilized while monitoring the evaporation rate of the material, an operation of opening the shutter and starting vapor deposition on the substrate surface is performed. This shutter covers the evaporation source and the substrate again at the timing of changing the substrate or changing the organic EL material to be deposited, so that the material deposited on the shutter facing the evaporation source may fall into the evaporation source due to the shock due to opening and closing. There is.

As a method of making the film thickness uniform, a method of increasing the distance between the evaporation source and the substrate is generally used together. Usually, a vacuum evaporation apparatus for an organic EL element uses a vessel such as a boat or a crucible as an evaporation source, and the organic EL vaporized from the evaporation source.
The gaseous molecules of the material spread and rise so as to exhibit an inverted triangular pyramid with the apex of the evaporation source, reach the deposition substrate, and are deposited. Then, in an arbitrary cross section of the inverted triangular pyramid, the concentration of gaseous molecules at the center is the highest, and the concentration decreases as the distance increases in the radial direction. The change in the concentration of gaseous molecules in the radial direction becomes larger as the position is closer to the evaporation source and closer to the center of the inverted triangular pyramid, and becomes smaller as they are further away. Therefore, in the film thickness distribution on the substrate, the thickness of the central portion of the gaseous molecules in the shape of an inverted triangular pyramid is large, and the thickness of the peripheral portion is small. Therefore, by increasing the distance between the evaporation source and the substrate, the concentration of gaseous molecules on the substrate surface can be averaged as much as possible, or only the periphery of the inverted triangular pyramidal gaseous molecular phase can be deposited on the substrate surface. In many cases, the thickness of the film is made uniform by performing the above method. However, in the former case, the spread of gaseous molecules becomes large, and a considerable amount of the gaseous molecules is deposited on the inner wall surface of the apparatus other than the substrate surface. In the latter case, there is an advantage that the device can be small in size, but gaseous molecules in the center of the inverted triangular pyramid at the highest concentration do not precipitate on the substrate surface. The problem of precipitation on wall surfaces and the like becomes more serious.

The organic EL deposited on the surface other than the substrate as described above
As the material accumulates, it may fall into the evaporation source and be co-evaporated.Therefore, it is important that the material deposited on parts such as the inner wall of the device and shutters that may fall into the evaporation source should not be altered. is there. In general, the organic EL material to be vapor-deposited is an expensive organic compound. Therefore, it is desired to collect and reuse the organic EL material. Therefore, in order to collect and recycle materials deposited on the inner wall surface of the device other than the substrate, it is important that the organic EL materials are not deteriorated.

In general, in a vacuum deposition apparatus for an organic EL element, a material of a portion where gaseous molecules of an organic EL material are deposited, such as a vacuum chamber main body, a shutter provided in the chamber, and an accessory including a so-called anti-adhesion plate. Austenitic stainless steel (sometimes abbreviated as SUS), which is inexpensive, has good workability, and is excellent in rust prevention, is often used as the material of components such as objects. However, depending on the organic EL material used, part of the precipitate is altered or contaminated. For example, in an organometallic complex compound such as 8-hydroxyquinoline aluminum (which may be abbreviated as Alq3), which is known as a typical organic EL material, iron in the SUS plate and aluminum in the organometallic complex are combined. A metal exchange reaction may occur to form an 8-oxyquinoline iron complex. This 8-oxyquinoline iron complex also vaporizes. When the organic EL material is corrosive or forms an oxidizing atmosphere, iron rust or the like is generated. Even when the organic EL material does not contain a metal element and is not corrosive, temperature changes occur repeatedly due to the operation and suspension of the apparatus, and as a result, the strongly adhered organic EL material and SU
Due to the difference in the coefficient of thermal expansion of the S metal plate, abrasion occurs on the SUS surface, and repeated stress is generated on the bonding surface between the SUS metal and the organic EL material. When the organic EL material is peeled off from the metal surface due to fatigue, a phenomenon that the surface structure of the micro convex portion on the metal surface is mechanically peeled off together may occur. When the deteriorated organic EL material falls into the evaporation source and is vaporized again and co-deposited on the substrate, the element performance deteriorates. Further, if there is a degraded substance in the recovered organic EL material, the regenerated substance is contaminated with impurities, and the performance of an element produced using the substance is reduced, or purification for recycling is difficult.

[0007]

SUMMARY OF THE INVENTION The present invention is directed to a method of manufacturing an organic EL device capable of preventing deterioration or contamination of an organic EL material and producing good quality organic EL devices with good yield, and is used in the method. The purpose of the present invention is to provide a device that can be used.

[0008]

According to the present invention, there is provided an organic EL thin film deposition method for forming a thin film by vaporizing an organic material for an organic EL device and depositing the organic material on a film forming substrate. This is a method for manufacturing an organic EL element in which an inner wall surface of an apparatus on which the substrate is deposited and a component installed inside the apparatus are made of a material inert to the organic material, and an organic EL thin film is deposited.
Further, the present invention vaporizes an organic material for an organic EL device,
In an organic EL thin film deposition method for forming a thin film by depositing a thin film on a film forming substrate, an inner wall surface of the apparatus on which the organic material is deposited other than the substrate surface and a component installed inside the apparatus are inert to the organic material. This is a method for manufacturing an organic EL element in which an organic material deposited on a surface other than the substrate surface is collected and reused.

Further, the present invention provides an apparatus for vapor-depositing an organic material for an organic EL element and depositing the organic material on a deposition substrate to form a thin film, wherein the organic material other than the substrate surface is deposited. This is an organic EL thin film deposition apparatus in which components installed on the inner wall surface and inside the apparatus are made inert with respect to the organic material. Further, the present invention is an organic EL thin film deposition apparatus in which the component is a shutter. Further, the present invention is an organic EL thin film deposition apparatus in which at least the surface layer of the inner wall surface of the device and the components installed inside the device are made of a material inert to an organic material to be vaporized.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an organic EL thin film deposition apparatus and a deposition method using the same according to the present invention will be described in detail. FIG. 1 is a schematic sectional view showing an example of the apparatus of the present invention. In the figure, 1 is a chamber, 2 is an evaporation source, and 3 is an organic E.
L material, 4 is a substrate, and 5 and 6 are shutters. In this drawing, the shutter 5 is provided near the evaporation source, and the shutter 6 is provided near the substrate. However, only one of them may be used.

The vacuum deposition apparatus in the above-described example is a holding means (shown in the drawing) for holding a chamber 1 which can be evacuated, an evaporation source 2 such as a crucible disposed in the chamber 1, and a substrate 4 at predetermined positions. ) And shutters 5 and 6 for controlling the timing of deposition substantially. The chamber 1 is configured to be capable of being depressurized by a vacuum pump or the like, and has a structure capable of taking in and out an organic EL material and a substrate charged therein. Then, the evaporation source 2 is heated, the pressure in the chamber 1 is reduced, and the organic EL material 3 charged in the evaporation source is vaporized (evaporated or sublimated) at a constant speed as much as possible. )
The organic EL attached to the substrate 4 by monitoring or controlling the vaporization speed and opening the shutters 5 and 6 when the vaporization speed becomes constant or controlling the degree of opening of the shutters 5 and 6 according to the vaporization speed. Control the rate or amount or thickness of material deposition.

In the vacuum evaporation apparatus of this embodiment, the shape of the evaporation source is crucible-shaped, but is not limited to this. Although only one evaporation source 2 is described,
There can be more than one. In addition, as components disposed in the chamber 1 and located at positions where the organic EL material adheres, only the shutters 5 and 6 are illustrated in order to simplify the drawing and to facilitate understanding, but usually other components are used. Many parts are installed. For example, an attachment-preventing plate that can be attached and detached in order to reduce the cleaning work of the material deposited mainly on the inner wall of the chamber may be installed.
This adhesion-preventing plate is formed by bending a thin SUS plate and installed in the chamber along the inner wall of the chamber, and is often divided and installed for easy attachment and detachment.

When the organic EL material is a material forming the light emitting layer, an organometallic complex is often used. However, when the complex metal comes in contact with a dissimilar metal at a high temperature, a certain percentage of metal exchange, that is, alteration occurs. Happens. Therefore, if the material other than the substrate on which the organometallic complex is deposited is not inert to the organometallic complex, the organometallic complex will deteriorate. The site where the organometallic complex is deposited besides the substrate is chamber 1
, The shutters 5 and 6 facing the evaporation source, and a so-called anti-adhesion plate. Chamber 1 and shutter 5,
The components such as 6 may be made of a material such as one kind of metal material, or may be made of two or more layers of materials. It is preferable to use a material that is inert to the EL material. Instead of using an inert material for the chamber 1, a so-called deposition-preventing plate may be used for the inert material.

The inert material referred to in the present invention is an organic EL.
A substance that does not cause deterioration, decomposition and contamination due to corrosion of the material not only in the material itself, but also in the organic EL material in contact with the material. Specifically, it refers to a material generated due to contact between the material of the chamber 1 and the like and the organic EL material, but includes a material that is corroded and deteriorated due to the atmosphere. However, this does not include the case where the organic EL material is simply thermally decomposed, but is limited to a material that promotes the decomposition and actually causes corrosion, alteration, and contamination in the atmosphere.
Materials preferably used in the present invention include noble metals such as gold, fluorine resins, polyimide resins, heat-resistant resins such as silicone resins, quartz glass, Pyrex (registered trademark),
Hard glass, glass such as enamel, alumina, silicon nitride,
Non-metallic materials, such as ceramics, such as porcelain, etc. are mentioned. It can be appropriately selected from these in consideration of workability, cost, and the like. Suitable inert materials include metals, glasses such as enamel, fluororesins, and ceramics. Among these, it is advantageous to use a material having no strength, difficult to mold, or an expensive material in such a way that only the surface layer is made inert by means such as thin film deposition or plating.

In the case of an organic metal complex EL material, in addition to the above inert material, a noble metal which does not cause a metal exchange reaction with the metal or a material having at least the same metal material as the metal on its surface can be used. . For example, Alq3
In this case, a material having a surface clad with aluminum can be used in addition to the aluminum material.

Next, a method for vapor deposition using the apparatus of the present invention will be described. The evaporation source 2 includes organic E to be deposited.
A predetermined amount of the L material 3 is charged. The substrate 4 on which some layers have already been provided by evaporation or the like is set with the surface to be evaporated facing the evaporation source 2 side. It is advantageous in terms of deposition rate that the substrate 4 is disposed almost directly above the evaporation source 2, but there is a risk that the deposits fall into the evaporation source 2 when the shutter is opened and closed or when the substrate is replaced. However, if the vapor deposition apparatus of the present invention is used, even in such a case, there is no alteration or contamination of the deposit, so that the problem caused by the alteration can be solved.

Thereafter, pressure reduction and heating are performed, and vaporization starts. The temperature of the evaporation source 2 and the surrounding evaporating section may be a temperature at which a predetermined vapor pressure of the organic EL material 3 can be obtained. Usually, this vapor pressure is on the order of several Torr to 10 ^-8 Torr. Immediately after the start of vaporization, the shutter covers the evaporation source or the substrate because the vaporization rate is not stable. The vaporization rate is monitored by a film thickness sensor or the like. When the vaporization rate is stabilized, the evaporation source or the shutters 5 and 6 covering the substrate are opened to start vapor deposition on the substrate. Other deposition conditions can employ a known method, and the present invention is not limited to the apparatus and operating conditions described in the above drawings or the following examples. Further, the organic EL material is not limited to a metal complex such as Alq3, but can be applied to all organic EL materials used for manufacturing organic EL elements.

[0018]

EXAMPLES Hereinafter, specific examples of the present invention will be described based on examples. Comparative Example 1 A custom-made high-purity 8-hydroxyquinoline aluminum (Alq3) was deposited on a substrate by using the deposition apparatus shown in FIG. The material of the shutters 5 and 6 was SUS304. After the deposition was completed, Alq3 deposited on the shutter 5 facing the evaporation source close to the evaporation source was recovered and analyzed. As a result, iron and chromium were detected. This was presumed to be a complex metal-exchanged with Alq3. Next, the collected Alq3 was collected and used as a light emitting layer and an electron transporting layer. Using the same apparatus as above, N, N'- was deposited on the ITO transparent electrode of the glass substrate on which the ITO film had already been formed. A stacked device having di- (naphthalen-1-yl) -N, N'-diphenyl-benzidine (hereinafter referred to as NPB) as a hole transport layer, followed by the Alq3, and then aluminum-lithium as a cathode was prepared. . The thickness of the organic material was set to 50 nm, and the electrodes were made of 200 nm for both ITO and aluminum-lithium.
And Observation of this device with a fluorescence microscope immediately after sealing revealed several dark spots per 1000 μm square. Example 1 A shutter was subjected to hot-dip aluminum plating, and Alq3 was deposited under the same conditions as in Comparative Example 1 except for that. Al deposited on the shutter 5 facing the evaporation source near the evaporation source after the end of the evaporation
No complex that had undergone metal exchange was detected in q3. This deposit was collected, and this was used as a light emitting layer and an electron transport layer, and a laminated device similar to that described in Comparative Example 1 was prepared under the same conditions as Comparative Example 1 using NPB as a hole transport layer. Observation of this device with a fluorescence microscope immediately after sealing revealed that the number of dark spots was significantly reduced.

[0019]

As described above, according to the present invention, it is possible to prevent deterioration of element performance by preventing deterioration of a material deposited at a portion which can be mixed into an evaporation source due to a mechanical shock or the like, and furthermore, it is intended to be used for recycling. Purification of the material to be recovered is also facilitated.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of an apparatus for vapor deposition of an organic EL element.

[Description of Signs] 1 chamber 2 evaporation source 3 organic EL material 4 substrate 5, 6 shutter

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Claims (5)

[Claims] In an organic EL thin film deposition for forming a thin film by vaporizing an organic material for an organic EL element and depositing the organic material on a film forming substrate, an inner wall surface and an apparatus on which the organic material is deposited other than on the substrate surface A method for manufacturing an organic EL device, wherein a component installed inside is made of a material inert to the organic material, and an organic EL thin film is deposited. 2. An organic EL thin film deposition method for forming a thin film by vaporizing an organic material for an organic EL element and depositing the organic material on a film forming substrate, wherein an inner wall surface of the apparatus on which the organic material is deposited other than on a substrate surface; An organic EL, wherein components installed inside the apparatus are made inert with respect to the organic material, and the organic material deposited other than on the substrate surface is collected and reused.
Device manufacturing method. 3. An organic EL thin film deposition method for vaporizing an organic material for an organic EL element and depositing the organic material on a film forming substrate to form a thin film. An apparatus for vapor-depositing an organic EL thin film, wherein a component installed inside is made of a material inert to the organic material. 4. The apparatus according to claim 3, wherein the component is a shutter. 5. The apparatus according to claim 3, wherein at least the surface of the inner wall of the device on which the organic material is deposited and at least the surface of a component installed inside the device are made of a material inert to the vaporized organic material. For organic EL thin film deposition.