Patent Application
20100092658
1. Technical Field
The present invention refers to a method of coating a substrate as well as a coating installation used therefore.
2. Prior Art
In various fields of prior art, for example semiconductor device manufacturing, solar panel manufacturing, organic light emitting diode (OLED) manufacturing, flat panel display (FPD) manufacturing and thin film transistor (TFT) manufacturing, it may be sometimes necessary to deposit one or more layers of material over the substrate, but only in selected areas. Depositing material in selected areas while not depositing in other areas of the same substrate can be complicated and expensive. Therefore, there is a need in the art for a method to deposit one or more layers over a substrate in preselected areas that is simple and affordable.
The use of shadow masks is expensive and the quality of the pattern decreases with an increasing number of coating processes due to deposition of coating material on the shadow mask. Therefore, the shadow mask has to be cleaned and exchanged intermittently. Photolithographic procedures, on the other hand, require a lot of equipment and a plurality of process steps and thus cause all in all high costs.
Consequently, efforts have been made to provide processes of manufacturing a structured or a patterned layer system which still have a high throughput, but are more cost efficient than conventional processes, while maintaining a high quality of the deposited structures.
It is therefore an object of the present invention to provide a coating method as well as a coating installation for depositing patterned structures, especially patterned electrodes or patterned moisture and oxygen barrier layers for OLED devices on large area substrates, wherein the method and installation allow an efficient production of high-quality structures. Moreover, the method should be easily performed, while the installation should be easy to be produced.
This object is achieved by a coating method having the features of claim 1 as well as a coating installation having the features of claim 16. Preferred embodiments are the subject matter of the dependent claims.
The inventors found that an easy, efficient and reliable way to produce patterned structures comprises depositing of a patterned mask layer by a printing method wherein the patterned mask layer comprises one or more balls. The mask material comprising one or more balls can be deposited very exactly and moreover the subsequent deposition of at least one layer or a stack of layers can be performed by sophisticated deposition methods, including vacuum deposition methods, sputtering methods, evaporation methods, plasma assisted coating methods, chemical vapour deposition (CVD) methods and/or physical vapour deposition (PVD) methods. It has been found that, although the patterned mask layer comprising the balls can be easily removed after the deposition of the subsequent layers, the subsequent deposited layers can be applied at a very high precision by the above-mentioned methods.
The method may be used for depositing metal materials like chromium, copper, titanium, tungsten, aluminium or the like and combinations thereof, transparent conductive oxides, like indium tin oxide (ITO), and/or semiconductor materials to form electrodes, electrode structures or current enhancement structures. Moreover, Fief barrier layers formed by carbon layers, especially amorphous carbon layers, and/or silicon nitride layers can also be deposited.
The structures, which can be formed, may comprise line structures or grid structures.
The current enhancement structure may improve the electrical properties, for example of an OLED device, e.g. for current distribution.
Although electrode layers or structures, for example on a glass substrate, are preferred embodiments for carrying out the present invention, various other kinds of layer systems may be deposited according to the inventive method and/or by using the coating installation according to the present invention. Moreover, a variety of different substrates may be used, for example substrates which already comprise at least one layer or a stack of layers.
The present method may comprise additional steps of providing additional layers, for example steps of providing an optoelectronic device layer for the emission of light. The additional layers may or may not be produced according to the present invention.
The mask material comprising the balls may be deposited by different printing methods including inkjet printing, screen printing, porous printing, pad printing and/or combinations of such printing methods.
The masking material may comprise in addition to the balls ink or other fluids which may act as carrier substance for the printing deposition. The ink or the other carrier fluids may be evaporated after printing.
The masking material may comprise in addition to the balls an adhesive in order to improve adhesion of the masking material to the surface of the substrate to be coated. Accordingly, the adhesive may be identical to or part of the carrier fluid mentioned above.
Alternatively, an adhesive may be deposited prior to depositing of the masking material including the balls. The adhesive may also be deposited by printing methods. The printing methods may be the same as for the masking material.
Although the balls of the masking material are designated as the balls, these balls may have a shape different to a sphere. Moreover, the balls may have the shape of blocks or posts. The balls may have different dimensions depending on the structure size to be achieved by the inventive method.
The balls may be formed by nanoparticles or microparticles having diameters in the range of a few run to hundreds of μm. Even balls having diameters of 0.5 mm to 1.5 mm may be used.
The masking material or patterned mask layer can be removed after the subsequent coating of the material to be structured by brushing, wiping, gas blasting, simple cleaning and combinations thereof.
A coating installation for carrying out the above-described method may comprise a printing tool for printing a patterned mask wherein the printing tool is adapted to print mask material comprising balls. In addition, the coating installation comprises a supply device for supplying mask material comprising balls. Moreover, the inventive coating installation comprises a process chamber, where the deposition of a coating layer can be performed according to at least one of the coating methods comprising vacuum deposition methods, sputtering methods, evaporation methods, plasma coating methods, chemical vapour deposition (CVD) methods and physical vapour deposition (PVD) methods. Accordingly, different material sources may be present in the coating installation, like carbon sources, silicon sources, nitrogen sources, silicon nitride sources, metal material sources, semiconductor material sources and TCO (transparent conductive oxide) material sources. In addition to the material sources mentioned above other material sources may be present depending on the kind of the patterned layer which has to be deposited.
In accordance with the method described above the coating installation may comprise printing tools like inkjet printer, screen printer or pad printing equipment as well as tools for removing the patterned mask material from the surface of the substrate or other coating equipment for subsequent coating of the substrate like equipment for depositing an organic electronic device onto the substrate.
Further advantages, characteristics and features become apparent by the following description of specific embodiments with respect to the attached drawings. The drawings show in a pure schematic way in
a to 1d a first embodiment of a method according to the present invention;
a to 2c a second embodiment of a method according to the present invention;
The embodiments disclosed in this application refer to methods of depositing a patterned first electrode of an organic electronic device on a substrate. However, the invention is not restricted to these applications. Instead of this, the various layer systems including also water barrier layers or current enhancement line or grid structures of OLED devices may be deposited according to the present invention.
The substrate on which the electrode is deposited according to the embodiments shown may be the carrier of a layer system deposited thereon. It may or may not comprise e.g. one or a plurality of light emitting layers, functional and/or protective layers, barrier layers, etc. The light emitting layer or layer stack may be deposited on top of the patterned first electrode.
In the first embodiment of the invention the method comprises providing a large-area substrate 1 and depositing a first semiconductor, metal, or TCO (Transparent Conductive Oxide) layer 3 (or a combination of a plurality of layers including one or more of said materials) on a surface of the substrate 1 as illustrated in
In a second process step illustrated in
In a third process step (
Afterwards, in a process step indicated in
Another embodiment of the invention is illustrated in
In a first step a substrate 1 is provided, and a layer of a masking material 2 is deposited directly on the surface of the substrate 1. The masking material 3 is deposited by using an inkjet printing method. The masking material layer 2 is patterned to form a structure on the surface of the substrate 1 which is inverse to the line- and/or grid-like structure of an electrode of an organic electronic device to be formed.
Afterwards, in a subsequent process step illustrated in
Afterwards, the masking material 2 and the metal material 3 deposited on top of the masking material 2 are removed from the substrate 1. Thereby, a patterned semiconductor, metal, or TCO (Transparent Conductive Oxide) layer 3 (line- or grid-like) is left directly on the surface of the substrate 1 forming a first electrode of an organic electronic device.
In this way the number of process steps may be reduced. Furthermore, it is not necessary to use a shadow mask for providing a patterned electrode layer on a substrate.
The adhesive 11 may comprise an epoxy. The balls 10 of the masking material may be made of metal, plastic, polymer and combinations thereof. The masking balls 10 may be deposited by ink jetting or other suitable printing methods. Instead of balls, blocks or posts or the like may also be used. Balls, blocks or posts may have diameters in the range of a few nm up to some tenth of nm or some hundreds of nm and moreover up to some μm. Even diameters of 0.5 mm to 1.5 mm are considerable. Although the balls 10 are shown to be touching each other, it is understandable that space may exist between the adjacent balls 10.
After the deposition of the coating layer 3 the balls 10 may be removed together with the adhesive 11 by blasting the surface of the substrate 1 with an inert gas at high pressure. As an example nitrogen may be used as the inert gas. Moreover, carbon dioxide may also be used to remove the adhesive 11 and the balls 10.
In another embodiment the adhesive 11 and the masking material comprising the balls 10 may be removed by brushing.
In the vacuum sub chamber 103 the printing device 300 is located, like an inkjet printer for producing the patterned mask layer as shown in
After the depositing of the patterned mask layer in the vacuum sub chamber 103 the substrate 110 is carried along the transport path 105 to the vacuum sub chamber 102 where the deposition of the electrode layer by a sputter process is performed. For this reason a twin magnetron electrode arrangement 200 is provided for sputtering a metal target. However, other materials may be deposited by other deposition technologies.
Although, printing of the patterned mask layer is shown to be performed in a vacuum chamber, the deposition of the patterned mask layer can also be performed in atmospheric environment. However, vacuum conditions may be advantageous with respect to oxidation and moisture problems which may arise with respect to the subsequent coating.
Although an installation for separate substrates, like large area glass substrates, silicon substrates or the like which are processed in a continuous way, are shown in
Although the present invention has been described with respect to specific embodiments, it is evident for a man skilled in the art, that the invention is not restricted to these embodiments, but that modifications and alterations are possible, for example omitting one or more of the features described or combining the features in a different way, without leaving the scope of the attached claims. The present invention especially comprises all combinations of the single features described herein.
