KR100569607B1 - Method for forming a passivation layer in organic emitting device - Google Patents

Abstract

The present invention is to deposit an inorganic buffer layer using chemical vapor deposition, sputtering, ion beam deposition or electron beam deposition on an organic light emitting device, to form an inorganic insulating film at a temperature of less than 20 to 100 ℃ by atomic layer deposition on the inorganic buffer layer It provides a method for forming a protective film of an organic light-emitting device comprising a step.

Through the above-described configuration, it is possible to avoid damaging the organic light emitting device from the precursor available when growing the thin film at low temperature by using the atomic layer deposition method can improve the life of the device, shorten the process time applied to mass production It becomes possible.

 Organic light emitting device, atomic layer deposition method, inorganic insulating film

Description

TECHNICAL FOR FORMING A PASSIVATION LAYER IN ORGANIC EMITTING DEVICE}

1 is a cross-sectional view of an organic light emitting device of the prior art.

2A and 2B are cross-sectional views of an organic light emitting diode shown in order to explain a method of forming a protective film of an organic light emitting diode according to an embodiment of the present invention.

The present invention relates to a method of forming a protective film of an organic light emitting device, and more particularly, to a method of additionally forming an inorganic buffer layer before forming an inorganic insulating film by atomic layer deposition.

In the high information age of the 21st century, the research and development of new futuristic display devices is of paramount importance. In particular, technologies related to the development of materials such as semiconductors and displays related to communication and computers have become a key factor, and in particular, organic electroluminescence (OEL or Organic Light Emitting Diode (OLED)) has attracted attention in terms of application to color display devices. I am getting it.

The organic light emitting diode has different characteristics from the conventional flat crystal display (LCD) and the field emission display (FED), plasma display panel (PDP) and electroluminescent display (ELD), and is a next generation display device. It is known as a flat panel display that can implement. Currently, glass substrates are used as LCD back-lights or portable display devices.

An organic light emitting device is a device in which electrons and holes generate an electron-hole pair in a semiconductor, and they emit light through a recombination process. In addition, the organic light emitting device has all three primary colors of light at a low driving voltage of less than 10V, the organic monomolecule is excellent in achieving high resolution and natural colors, the organic polymer can be manufactured at a low cost, large area, This has the advantage of being flexible and having a fast response time.

Looking at the structure of the organic light emitting device, an injection type thin film device manufactured with a light emitting layer and a transporting layer has a common point with an inorganic semiconductor as a light emitting device using a PN junction, but is recombined by injection of a small number of carriers at the junction interface. Unlike the PN junction type LED, which is governed by recombination, in the case of the organic light emitting device, there is a slight difference in that all the carriers that contribute to light emission are injected from an external electrode. That is, the carrier injection type light emitting device needs an organic material which is easy to inject and move carriers.

The stacked structure of the organic light emitting device can be largely divided into a single layer and a multi-layer. Here, the organic light emitting device having a multilayer structure will be described with reference to FIG. 1.

1 is a cross-sectional view of an organic light emitting diode shown in order to describe a multilayered organic light emitting diode. The organic light emitting diode includes a substrate 10, an anode electrode 12, a hole injection layer 14, a hole transport layer 16, The light emitting layer 18, the electron transport layer 20, the electron injection layer 22, and the cathode electrode 24 are laminated.

However, the organic light emitting device has a deterioration due to internal factors such as deterioration due to oxygen of the cathode electrode, deterioration of the light emitting layer due to oxygen from ITO (Indium Tin Oxide), and deterioration due to the reaction between the light emitting layer and the interface. , Deterioration easily occurs due to external factors such as oxygen, ultraviolet rays, and fabrication conditions of the device. In particular, the packaging of the organic light emitting device is very important because the external oxygen and moisture have a fatal effect on the life of the device.

Although there is little report on the technology of the packaging of the organic light emitting device, one of the most used technologies is a method of covering a passivation metal can 26 toward the cathode electrode as shown in FIG. have.

Another technique for packaging an organic light emitting device is disclosed in US Patent No. 5,952,778 ('Encapsulated organic light emitting device'), registered March 18,1997. The technique of U.S. Patent No. 5,952,778 continuously deposits a metal, such as aluminum (Al) or transition metal, which is relatively less sensitive to moisture or oxygen on an organic light emitting device cathode electrode in a vacuum state using a mask such as a cathode electrode. Afterwards, a silicon oxide film or a silicon nitride film (Ion Beam Deposition), Electron Beam Deposition (Plasma Beam Deposition), or Chemical Vapor Deposition (Chemical Vapor Deposition) may be used. A method of encapsulating an organic light emitting device by forming an inorganic insulating film such as silicon nitride and forming a lipophilic polymer such as polysiloxane and polytetrafluethtylene thereon. .

However, the inorganic insulating film forming method according to the prior art has a disadvantage that the deposition temperature must be high, the coverage of the thin film is not excellent, and the density of the thin film is not dense, and thus it is necessary to have an excellent film quality at a lower temperature. The use of the protective film of the device has a limitation.

In addition, US Pat. No. 5,496,597 describes a technique for inorganic insulating thin film manufactured by atomic layer deposition, and proposes a new method using various organometallic compounds to form an insulating film of an electroluminescent device. In particular, since the breakdown voltage is high and the leakage current is required, all of them are proposed only for the high temperature processing method, and the low temperature processing method is not disclosed at all.

In addition, 'Dependence of atomic layer-deposited Al ₂ O ₃ films characteristics on growth temperature and Al precusor of Al (CH ₃ ) ₃ and' published in 'J.Vac.Sci.Technol.A' in 1997 by 'SJYun'. prior paper of AlCl ₃ 'is in the aluminum oxide insulating film is formed as a description of the change in the characteristic according to the type and the growth temperature of the Al precursor, a technique related to the above 250 ^o C high temperature process as well.

As described above, the inorganic insulating film manufacturing method according to the related arts presented so far has a disadvantage that the deposition temperature is high, the coverage of the thin film is not excellent, and the density of the thin film is not dense, which is excellent at a lower temperature. There is a need for a production method capable of forming an inorganic insulating film of performance. In particular, as the modern society rapidly develops into an information society, the demand for display technology is becoming more sophisticated and diversified. As a result, the demand for a rollable display (Foldable Display or Flexible display) is increasing. In manufacturing a display using a plastic substrate such as a digital paper, including a light emitting device, it is essential to form an inorganic insulating film at a low temperature so that cheap plastic is not denatured.

On the other hand, in order to satisfy this demand, a technique for forming a protective film at low temperature has been developed. As a manufacturing technology for a protective film that can protect an organic light emitting device from oxygen or moisture at low temperature, a technique using atomic layer deposition atomic layer epitaxy is disclosed in US Patent US2001 / 0052752A1; US 2002 / 0003403A1 Thin Film Encapsulation of Organic Light Emitting Diode Device. This technique describes the use of a multilayered structure of an oxide film and an organic material deposited using ozone as an oxygen precursor at a temperature of 100-120 ° C. as a protective film. The oxide film deposited by the atomic layer deposition method may be a protective film in direct contact with the organic light emitting device, or may be deposited with an organic material that is a polymer in between.

However, in the case of forming a protective film by the atomic layer deposition method according to the prior art, the organic light emitting device has a large damage due to heat at a temperature of 100 ° C. or higher, and in particular, a protective film is formed on the device by using ozone by atomic layer deposition. In this case, the life of the device is shortened due to the damage of organic materials due to ozone.

In addition, the atomic layer deposition method according to the prior art has a disadvantage in that the growth time for growing a thin film having a required thickness is longer than several ten minutes because the growth rate is not high, thereby shortening the lifespan of the organic light emitting device and increasing the processing time during mass production.

Therefore, there is an urgent need for a technology that can form a protective film at low temperature, thereby reducing damage due to heat of the organic light emitting device and shortening growth time to facilitate mass production, and to form a thin film having excellent characteristics.

Accordingly, an object of the present invention is to solve the above problem, to form a protective film for protecting the organic light emitting device at a low temperature.

Another object of the present invention is to improve the life of the device in order to avoid damaging the organic light emitting device from the precursor available when growing the thin film at low temperature using atomic layer deposition.

Another object of the present invention is to shorten the protective film formation time to facilitate mass production.

As a means for solving the above problems, the first aspect of the present invention is a method for forming a protective film of an organic light emitting device, the deposition of an inorganic buffer layer on the organic light emitting device using chemical vapor deposition, sputtering, ion beam deposition method or electron beam deposition method And forming an inorganic insulating film on the inorganic buffer layer by atomic layer deposition, and forming the inorganic insulating film by using a surface chemical reaction of precursors containing elements constituting the organic insulating film at a temperature of less than 20 to 100 ° C. A protective film forming method of a light emitting device is provided.

The second aspect of the present invention is to deposit an inorganic buffer layer using chemical vapor deposition, sputtering, ion beam deposition or electron beam deposition on the entire substrate or one surface, and to form an inorganic insulating film by atomic layer deposition on the entire substrate, the inorganic insulating film Formation of the protective film of the organic light-emitting device comprising a step of depositing at a temperature of 20 to 100 ℃ using a surface chemical reaction of the precursor containing the element constituting it, and manufacturing an organic light emitting device on the inorganic insulating film It provides a formation method.

Hereinafter, with reference to the accompanying drawings will be described an embodiment of the present invention; However, embodiments of the present invention may be modified in various forms, and the scope of the present invention should not be construed as being limited by the embodiments described below. Embodiments of the present invention are provided to more fully describe the present invention to those skilled in the art.

(First embodiment)

FIG. 2A is a cross-sectional view of an organic light emitting diode shown in order to explain a method of forming a protective film of an organic light emitting diode according to a first embodiment of the present invention, and FIG. 2A is a cross-sectional view of an organic light emitting diode emitting light downward.

First, an organic light emitting diode that emits light downward will be described with reference to FIG. 2A. The anode electrode 102, the hole injection layer 104, the hole transport layer 106, the light emitting layer 108, the electron transport layer 110, the electron injection layer 112 on the transparent substrate 100 made of a glass substrate or plastic, etc. And an organic light emitting diode in which the cathode electrode 114 is stacked.

The type of the substrate 100 is not particularly limited and can be variously used. For example, a glass substrate, a plastic substrate, or a silicon substrate mainly applied to an EL of a top emission type may be used.

The anode electrode 102 has a high work function as an electrode for hole injection, uses a transparent metal oxide so that emitted light can come out of the device, and the most widely used hole injection electrode is ITO (Iindium Tin Oxide). About 50 to 200 nm. ITO has the advantage of optical transparency, but has the disadvantage of not easy to control. Therefore, recently, chemically-doped conjugated polymers including polythiophene (PT), etc., which have advantages in ambient stability, have been considered for use as hole injection electrodes. In this case, by using a metal having a high work function as the anode electrode 102 material, it is possible to prevent a decrease in efficiency through non-luminescence recombination in the anode electrode 102.

The hole injection layer 104 serves to supply holes supplied from the anode electrode 102 to the hole transport layer, while the hole transport layer 106 is a TPD which is a diamine derivative and poly (9) which is a photoconductive polymer. -vinylcarbazole, and the electron transport layer 110 uses an oxadiazole derivative, and the like, and the combination of these transport layers increases the quantum efficiency (Photons Out Per Charge Injected), and the carrier layer is not directly injected. The driving voltage can be lowered through a two-stage injection process. In addition, when the electrons and holes injected into the light emitting layer 108 move to the opposite electrode through the light emitting layer 108, the recombination can be controlled by blocking the opposite transport layer. Through this, the luminous efficiency can be improved. Single excitons generated by the recombination of electrons and holes are formed at the interface between the electrode and the light emitting layer to prevent quenching (the phenomenon that the light emission of the material slows down as the light emitting molecules near each other).

The light emitting layer 108 is made of mono-molecular organic EL materials such as Alq ₃ , anthracene, etc., and polymer organic EL materials such as poly (p-phenylenevinylene) (PPV), polythiophene (PT), or derivatives thereof. In order to discharge charges at a voltage, a study on thinning of the light emitting layer (EML) 18 (for example, 100 nm) is underway.

The electron transport layer 110 and the electron injection layer 112 are formed on the opposite side of the hole injection layer 104 and the hole transport layer 106 with the light emitting layer 108 interposed therebetween, and the anode electrode 102 of the organic light emitting device Holes are injected into the light emitting layer 108 through the transport layer 104, and the cathode electrode 114 injects electrons into the light emitting layer 108 through the electron injection layer to form electron-hole pairs in the light emitting layer 108. As they are combined, light is emitted by radiating energy.

Cathode electrode 114 is used as the electrode for electron injection, Ca, Mg, Al, etc., a metal having a small work function is used. The reason for using the metal having a low work function as the electron injection electrode is to obtain a high current density in electron injection by lowering a barrier formed between the cathode electrode 114 and the emission layer 108. Because it can. Therefore, while Ca having the lowest work function shows high efficiency, Al has a relatively high work function and thus has low efficiency. However, Ca has a problem of being easily oxidized by oxygen or moisture in the air, and Al has a relatively stable property in air.

After forming the organic light emitting device through the above process, a protective film 118 for protecting the organic light emitting device is formed.

The passivation layer 118 may be configured to include an inorganic buffer layer and an inorganic insulating layer. The inorganic buffer layer is formed of Al ₂ O ₃ , AlON, AlN, SiO ₂ , Si ₃ N ₄ , SiON formed by one of CVD (ICP-CVD, PECVD, LPCVD, APCVD, etc.), sputtering, ion beam deposition, and electron beam deposition. , MgO thin film or a multi-layered film composed of two or more thereof, and the inorganic insulating film is aluminum oxide, aluminum nitride, aluminum oxynitride, silicon oxide, silicon nitride deposited at a temperature of less than 100 ℃ using atomic layer deposition method It may be a multilayer film made of any one or a combination of two or more of these. The inorganic insulating film may be formed to a thickness of approximately 15 to 50 nm, and the inorganic buffer layer may be formed to a thickness of 100 to 200 nm.

In addition, an organic insulating film may be added between the organic light emitting element and the inorganic insulating film. The organic insulating film can use a vacuum deposition method and a spin coating method. For example, a thermal chemical vaporization of a monomer and vacuum deposition forms a TCVDPF (Thermal Chemical-Vapor-Deposition Polymer) thin film. The kind of the polymer is not particularly limited, and various kinds are possible, for example, parylene, teflon, polyacrylate, and the like. The thickness of the organic insulating film is formed to about 1 to 5 mu m in thickness.

In addition, a metal film can be added on the inorganic insulating film. The metal film can be deposited to, for example, about 100 nm using thermal evaporation, sputtering, atomic layer deposition, or the like. The addition of such a protective film metal film has the effect of increasing the moisture protective properties, it is possible to improve the properties of the protective film.

Hereinafter, a method of forming an inorganic insulating film using the atomic layer deposition method will be described in detail.

The organic light emitting device may be formed by growing an inorganic insulating film using an atomic layer deposition method at 100 ^° C or less so as not to damage the organic light emitting device. The inorganic insulating film is, for example, aluminum oxide, zinc oxide (ZnO) titanium oxide, tantalum oxide, zirconium oxide (ZrO ₂ ), hafnium oxide (HfO ₂ ), silicon oxide (SiO ₂ ), silicon nitride (Si ₃ N ₄ ), aluminum nitride (AlN), aluminum oxynitride (AlON) and the like can be deposited by atomic layer deposition.

Representative examples of the atomic layer deposition methods include a traveling wave reactor type including a shower head method and a plasma-enhanced atomic layer deposition method. In the case of the plasma enhanced atomic layer deposition method, it is divided into a remote plasma atomic layer deposition method and a direct plasma atomic layer deposition method according to a plasma generator.

In this embodiment, any of these atomic layer vapor deposition methods may be used, and one of these may be used or two or more may be used in combination. The protective film layer may be formed by a mixed deposition method in which two or more of the traveling type and the plasma type are used in combination. However, in order to see the effect of simultaneously coating both sides of a device or a substrate, a traveling wave reactor type deposition method is most preferred.

When growing aluminum oxynitride (AlON) thin film through plasma-enhanced deposition method, trimethylaluminum is used as a precursor of aluminum and ammonia and oxygen or oxygen and nitrogen are used as precursors of oxygen and nitrogen at low temperatures below 60 ^o C. High quality thin film can be formed.

Particularly, aluminum nitride (AlN) can be formed using trimethylaluminum and ammonia plasma, and in this case, a multilayer structure that can cause microcavity effect is formed through a multilayer structure with alumina having a refractive index of 1.6 to 1.7. In addition to improving the lifespan, there is also an effect that can improve the luminous efficiency.

In addition, the high thermal conductivity of aluminum nitride also has the advantage of reducing the damage of the device caused by the heat when the electrode is used as a protective film of the plastic substrate.

Next, a method of forming an aluminum nitride film with an inorganic insulating film will be described.

Al-precursor (e.g. trimethyl aluminum) vapor with carrier gas such as nitrogen or argon into the chamber, with the organic light emitting element placed in a chamber of semiconductor deposition equipment having an internal temperature of 60 ^° C., for example. Is injected into the chamber.

As a result, the Al-precursor reactant is adsorbed on the surface of the organic light emitting device. Next, the gas valve of the chamber is opened and nitrogen or inert gas is injected.

By this process, all of the molecules that are not adsorbed on the surface of the organic light emitting device among the Al-precursor reactants are removed. Next, NH ₃ is injected into the chamber and plasma is generated at the same time.

Next, the Al-precursor reactant adsorbed on the substrate and the plasma NH ₃ react with the surface to form an aluminum nitride thin film to generate volatile byproducts. Then, the gas valve of the chamber is opened and nitrogen or inert gas is injected. This step removes excess volatile reaction products.

Preferably, the desired aluminum nitride thin film can be obtained by repeating the above-described series of steps several times. The process is repeated hundreds of times until an inorganic insulating film having a desired thickness is formed.

In order to apply to the organic light emitting device, it is preferable to form a thickness of 15 to 50nm in consideration of the hygroscopicity and the process time. The thickness of the aluminum nitride film depends on how many times one cycle of the above-described process is performed. In addition, the deposition time according to one cycle varies depending on the conditions such as the injection amount of the precursors, and the injection amount of the precursors also depends on the size of the substrate.

Next, the process sequence of forming an aluminum oxide film with an inorganic insulating film is demonstrated.

First, the organic light-emitting device in which all active layers except the protective film of the inorganic insulating film by the atomic layer deposition method are formed is placed in a chamber of a semiconductor deposition apparatus in which an internal temperature is maintained at, for example, 80 ° C., and transports nitrogen or argon into the chamber. Trimethylaluminum vapor is injected into the chamber along with the carrier gas. As a result, the Al-precursor reactant is adsorbed on the surface of the organic light emitting device.

Next, the gas valve of the chamber is opened and nitrogen or inert gas is injected. By this process, all of the molecules which are not adsorbed on the surface of the organic light emitting element in the Al-precursor reactant are removed.

Next, the gas valve of the chamber is opened and H ₂ O gas is injected. At this time, the H ₂ O gas is surface-reacted with the Al-precursor reactant adsorbed on the substrate to grow an aluminum oxide thin film to generate volatile byproducts.

Then, the gas valve of the chamber is opened and nitrogen or inert gas is injected. This step removes the volatile reaction product between the Al precursor and H ₂ O, including the extra H ₂ O molecules.

For example, a desired aluminum oxide thin film having a thickness of 20 nm can be obtained by repeatedly performing the above-described series of steps 200 times. On the other hand, in order to apply to the organic light emitting device it is preferable to form a thickness of 15 to 50nm in consideration of the moisture absorption and the process time.

When the temperature of the aluminum oxide film is grown and the characteristics of the thin film are examined, it is observed that the aluminum oxide film is not grown when the water precursor is used below 70 ° C., whereas the plasma precursor is used at room temperature. A thin layer of aluminum nitride is grown to produce volatile byproducts. In addition, it was observed that the aluminum oxide film was grown, and when it exceeds 100 ° C, the luminance of the organic light emitting device was observed to be decreased, and when used as a protective film, the deposition temperature was increased to a temperature suitable for the thermal characteristics of each plastic substrate. On the other hand (eg PES-180 ℃, PET-100 ℃), less than 100 ℃ is appropriate when used as an insulating film to protect the light emitting device itself.

Using a similar method, a protective film of silicon oxide (SiO ₂ ), silicon nitride (Si ₃ N ₄ ), silicon oxynitride (SiON), aluminum nitride (Al ₂ O ₃ ), aluminum oxynitride (AlON), or the like In the case of nitride or oxynitride, it is preferable to deposit using plasma by the method described above, and in the case of aluminum oxide, it is preferable to use a water precursor.

On the other hand, in addition to using each single film such as an oxide film and a nitride film, a multilayer structure thereof can be formed. That is, it is possible to implement by controlling Al ₂ O ₃ / double layer, Al ₂ O ₃ / AlN / Al ₂ O ₃ thickness of less than 1 angstrom all the same layered structure of the AlN. In this case, a single passivation layer (eg, alumina) may be deposited by using two or more atomic layer deposition methods, which are initially several nm deposited by a traveling method, followed by deposition of the same passivation layer using a plasma enhanced method. This is because it can be secured. The protective film of a multilayer structure can also be deposited using two or more atomic layer deposition methods.

For example, travel to use Al ₂ O ₃ layer formed by a direct plasma method in a ring atom layer deposited by vapor deposition Al ₂ O ₃ layer together to form a multi-layer structure of an inorganic insulating film of the protective film, and treble ring atom layer may be constructed a multi-layer structure of the AlN layer formed by the direct plasma atomic layer deposition onto the Al ₂ O ₃ layer formed by the vapor deposition method. As such, it is possible to form various protective films by various atomic layer deposition methods using various reactive precursors.

In addition, in order to increase the light emission characteristics of light in a specific wavelength range, by depositing by atomic layer deposition at low temperature, a layered structure of a nitride film having a high film quality and a high refractive index and an oxide film having a relatively small refractive index is improved to improve the characteristics of the protective film. Of course, the microcavity effect can be obtained at the same time.

Experimental Example

An inorganic thin film used as a buffer layer on the substrate was deposited by ICP-CVD to observe moisture permeation characteristics. According to the deposition conditions, it showed different characteristics, and the deposition rate of 9.58 nm / min had a characteristic of 1.38 g / m ² .day at 200 nm thick Si _x N _y deposition. In addition, when the deposition rate of 11.5 nm / min at 600nm thickness deposition was 0.96 g / m ^2. The moisture permeability was shown in this case, because the process takes more than 50 minutes, there is a problem in mass production.

In addition, the SiN single layer deposited by PECVD has a moisture permeability of 60 g / m ² .day @ 100% RH or more, but when it is used as an inorganic buffer layer, an inorganic insulating film is formed on the SiN by atomic layer deposition. It can cover all possible pinholes, thus forming an effective protective film.

Meanwhile, Table 1 shows the moisture permeability characteristics of the aluminum oxide thin films grown simultaneously on both sides of the substrate using trimethylaluminum and water as precursors at 80 ° C. by atomic layer deposition to be formed on the inorganic buffer layer.

Number of aluminum oxide processes (deposition thickness) Breathability (g / m ² .day @ 100% RH) 125 (12.5 nm) 11.52 150 (15 nm) ~ 4 200 (20 nm) 0.25 250 (25 nm) 0.21 500 (50 nm) 0.118 1000 (100 nm) 0.498

According to Table 1, the moisture permeability of the aluminum oxide thickness is drastically decreased in the region between 12.5 and 200 nm, and gradually increases in the region between 50 and 100 nm. However, it was observed that the time to deposit a thickness of 50 nm or more was not suitable for mass production. Therefore, a thickness of 15 nm to 50 nm is preferable for forming a protective film of an organic light emitting device for application to mass production through an appropriate process time.

Looking at Table 1, the moisture permeability of the 200 nm thick inorganic insulating film formed by PECVD, ICP-CVD, ECR-CVD, etc. is largely 60g / m ² .day @ 100% RH at least 1 ~ 2 g / m ² .day Compared with @ 100% RH, the moisture permeability of the aluminum oxide film deposited at 250 steps was better.

On the other hand, when the thickness of the thin film is increased, for example, 50 nm or more, the damage of the device or the substrate is caused by the increase of the processing time, and the characteristics as the protective film are further lowered. When the temperature was increased to 120 ° C. for the burn process, the moisture permeation property was further lowered.

Therefore, it can be seen that the inorganic insulating film formed by the atomic layer deposition method is less than 50 nm and the temperature is less than 100 ° C. due to the damage of the organic material due to the process temperature rise. On the other hand, if the atomic layer deposition method is performed using a plasma, it is possible to deposit the film even at room temperature.

Next, before forming the inorganic insulating film by the atomic layer deposition method, after forming a 200 nm Si ₃ N ₄ film using PECVD at room temperature as an inorganic buffer layer, the moisture permeability characteristics of the protective film deposited with aluminum oxide at 80 to 200 process recovery was measured. It was. The water vapor transmission rate was 0.055 g / m ² .day @ 100% RH, indicating sufficient protective film characteristics of the organic light emitting diode. This exhibits excellent water vapor permeability compared to a protective film composed of only a Si ₃ N ₄ film having a thickness of 200 nm.

The characteristics of SiN single layer deposited by PECVD are SiN single layer deposited by PECVD when the SiN film is formed by atomic layer deposition method on SiCVD single layer deposited by PECVD, compared with the moisture permeability of 60 g / m ² .day @ 100% RH or more. It is analyzed that an effective protective film can be formed because it can cover all the pinholes present in the film.

Therefore, when the inorganic buffer layer is formed, a superior protective film can be obtained when using a multilayer structure in which an inorganic insulating film is formed by atomic layer deposition.

Meanwhile, an organic insulating layer may be further added between the organic light emitting element and the inorganic buffer layer. In the case of using parylene as the organic insulating film, it was confirmed that the moisture permeation effect according to the deposition temperature of -30 ~ 20 ℃ is not significantly different. When when the deposition temperature is 20 ℃ the moisture permeability varies depending on the thickness of the thin film is deposited on the moisture permeability PES substrate showing 92g / m ² .day, for 2nm 55g / m ² .day, for 3nm 30g / m ² .day In the case of 5.5nm, the moisture permeability of 25g / m ² .day and 15g / m ² .day is 12nm.

When the organic insulating layer is deposited, although the moisture permeability of the substrate is good, if the process time is excessive, the organic light emitting device may be affected. That is, the organic insulating layer mainly reduces the stress between the thin films to maintain the bending of the substrate, prevents pinholes when forming the multilayer structure with the inorganic material, and in particular, in the case of the present invention, the physical layer of the organic light emitting element when the inorganic material is deposited, The role as a buffer layer to protect from chemical damage is greater, in which case less than 5 μm is preferred. In particular, parylene has a lower deposition rate than other polymer deposition rates, and thus, the deposition time of 12 μm is consumed for 5 hours or more, resulting in damage to the organic light emitting device and poor moisture permeability.

When the protective film is formed on the organic light emitting device, an organic insulating film such as parylene may be directly formed on the device to prevent precursors such as water or plasma from directly contacting the light emitting device and being deposited by atomic layer deposition. However, in the case of aluminum nitride, since a thin film is formed without using oxygen or water, in this case, it is also possible to form an inorganic insulating film directly on the organic protective film by atomic layer deposition without forming an inorganic buffer layer.

Figure 2b is a cross-sectional view showing an organic light emitting device of the top emission method of emitting light to the top according to an embodiment of the present invention.

Unlike the organic light emitting device illustrated in FIG. 2A, a cathode electrode 114, an electron injection layer 112, an electron transport layer 110, and an emission layer are disposed on an opaque substrate 200 such as Si, for emitting light upward. An organic light emitting device is formed in a structure in which the structure 108 is stacked with the hole transport layer 106, the hole injection layer 104, and the anode electrode 102. Another organic light emitting device may have a structure in which the upper metal electrode (cathode) is deposited to be transparent, and then the transparent electrode is formed thereon in the same form as the case of emitting light downward. A protective film 118 is formed to protect the organic light emitting device manufactured as described above. In this case, the method of forming the protective film is as described above.

Meanwhile, as described with reference to FIG. 2B, in the case of the organic light emitting device in which the cathode electrode 114 is used as the lower electrode adjacent to the substrate 200 and the anode electrode 102 is used as the upper electrode, ITO, ZnO: Al as the upper electrode. Transparent oxide electrodes, such as these, are deposited.

However, when the metal film is added to the protective film, the film may become opaque depending on the thickness of the film. Therefore, when the metal film is used to emit light with the top emission structure, it is preferable to reduce the thickness.

(Second embodiment)

In another embodiment according to the present invention, the inorganic buffer layer is deposited on the whole or one surface of the substrate by chemical vapor deposition, sputtering, ion beam deposition, or electron beam deposition. In this case, the inorganic buffer layer may be formed only on one surface of the substrate on which the organic light emitting device is to be manufactured.

Next, an inorganic insulating film is formed on the whole substrate at the temperature of 20-100 degreeC by atomic layer vapor deposition. The inorganic insulating film of the low temperature process is, for example, aluminum oxide, zinc oxide (ZnO), titanium oxide (Titanium Oxide), tantalum oxide (Tantalum Oxide), zirconium oxide (ZrO ₂ ), hafnium oxide (HfO ₂ ), silicon oxide (SiO ₂ ) , Silicon nitride (Si ₃ N ₄ ) aluminum nitride (AlN), aluminum oxy nitride (AlON) can be deposited. Preferably, when the deposition process is performed by a traveling atomic layer deposition method, it is possible to form an inorganic insulating film on the entire substrate (both sides and side surfaces).

In this case, for the purpose of protecting the substrate on all or part of the top, bottom and side surfaces of the substrate (e.g., only on the top surface of the substrate on which the element is to be formed) or to prevent impurities from the substrate from entering the element. It can be used for the purpose.

In particular, UV-Vis spectra of aluminum oxide and the like show better transmittance than the plastic substrate itself by refractive index, thereby showing suitable characteristics as a protective film of the device. Therefore, it becomes possible to form the whole substrate as a protective film using such a characteristic.

In addition, an organic insulating film may be deposited between the organic light emitting element and the inorganic insulating film. In addition, it is also possible to make a metal film into one structure of a protective film.

In addition, the bending of the substrate caused by the formation of the protective film on only one surface of the substrate including the organic light emitting device is also one of the big problems of the plastic device is also an important point that the deposition can be easily coated on both sides.

In the description of the present invention mainly described in detail based on the organic light emitting device, the present invention can be applied to various organic electronic devices manufactured by moisture-sensitive electronic devices, particularly plastic substrates, including organic materials such as organic transistors.

In conclusion, although the technical spirit of the present invention has been described in detail according to the above-described preferred embodiment, it should be noted that the above-described embodiment is for the purpose of description and not of limitation. In addition, those skilled in the art will understand that various embodiments are possible within the scope of the technical idea of the present invention.

Therefore, according to the present invention, an inorganic insulating film is formed as a buffer layer in order to reduce chemical damage of the light emitting device that may be received due to the precursor constituting the thin film during atomic layer deposition, thereby improving the life of the organic light emitting device.

Not only can a protective film having excellent properties at low temperatures can be manufactured, but it can also reduce the processing time as well as the organic light emitting device, thereby providing a protective film suitable for mass production.

Claims (10)

In the method of forming a protective film of an organic light emitting device, Depositing an inorganic buffer layer on the organic light emitting device by chemical vapor deposition, sputtering, ion beam deposition, or electron beam deposition; And Form an inorganic insulating film on the inorganic buffer layer by atomic layer deposition, the formation of the inorganic insulating film is characterized in that the deposition at a temperature of less than 20 to 100 ℃ using the surface chemical reaction of the precursors containing the element constituting it A protective film formation method of an organic light emitting element. Depositing an inorganic buffer layer on the whole or one surface of the substrate by chemical vapor deposition, sputtering, ion beam deposition, or electron beam deposition; Forming an inorganic insulating film on the entire substrate by atomic layer deposition, and forming the inorganic insulating film using a surface chemical reaction of precursors including elements constituting the inorganic insulating film at a temperature of 20 to 100 ° C .; And And forming an organic light emitting device on the inorganic insulating film. The method according to claim 1 or 2, And an organic insulating layer between the organic light emitting device and the inorganic buffer layer. The method of claim 3, wherein The organic insulating layer is a protective film forming method of the organic light emitting device, characterized in that deposited to 1 to 5 ㎛ thickness. The method of claim 4, wherein The organic insulating film is a TCVDPF thin film, parylene, Teflon or poly acrylate, characterized in that the protective film forming method of the organic light emitting device. The method according to claim 1 or 2, The inorganic insulating film is formed to a thickness of 15 to 50nm, the inorganic buffer layer is formed a protective film of the organic light emitting device, characterized in that formed to a thickness of 100 to 200nm. The method according to claim 1 or 2, A method of forming a protective film for an organic light emitting device, further comprising a metal film on the inorganic insulating film. The method according to claim 1 or 2, The inorganic insulating film is formed by depositing the same film or a double film using at least two kinds of atomic layer deposition methods. The method according to claim 1 or 2, The inorganic buffer layer is an Al ₂ O ₃ , AlON, AlN, SiO ₂ , Si ₃ N ₄ , SiON, MgO thin film or a multilayer film made of a combination of two or more. The method according to claim 1 or 2, The inorganic insulating film is a protective film forming method of an organic light-emitting device, characterized in that the multilayer film made of any one or a combination of two or more of aluminum oxide, aluminum nitride, aluminum oxynitride, silicon oxide, silicon nitride.

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