JP2009161823A - Vapor deposition method, and vapor deposition system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vapor deposition method for collectively forming multilayer films. <P>SOLUTION: Two-dimensionally arranged vapor deposition sources 110 are divided into three groups 111, 112, 113 per vapor deposition material correspondingly to the number of layer configurations, and the vapor deposition sources of the respective groups can be independently heated and controlled respectively by heating elements 120 (121, 122, 123). The respective vapor deposition sources 110 successively evaporate ≥95% of the packed materials per group in the film deposition of the respective layers. Multilayer films composed of a plurality of organic material layers can collectively be formed even without performing the exchange of the vapor deposition sources. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a vapor deposition method and a vapor deposition apparatus for forming a multilayer organic film of an organic EL element.

  In recent years, organic EL elements have been studied as thin display elements instead of liquid crystal display elements. Compared to the case where the former forms an image by providing liquid crystal as a shutter on a panel (backlight) that emits light from the entire surface, the latter emits light at the necessary brightness with the necessary brightness, so it is superior in visibility and power saving. ing. Further, since a backlight is not required, it is advantageous for thinning.

  In order to form an organic material layer constituting an organic multilayer film of an organic EL element, a vapor deposition method is generally used. However, when vapor deposition is performed on a large area using a single crucible, vapor deposition is performed to ensure film thickness uniformity. It was necessary to secure a considerable distance between the source and the deposition target. This leads to an increase in the size of the film forming apparatus and a reduction in material use efficiency. In addition, since a desired film thickness is formed after controlling the deposition rate, the control by the film thickness monitoring causes an actual film thickness and an error, which tends to reduce the yield. Furthermore, there are concerns about maintenance problems such as clogging of the crucible due to prolonged use and deterioration of the vapor deposition material.

  As a vapor deposition technique for solving these problems, a method is proposed in which a vapor deposition material support layer formed uniformly with a vapor deposition material is opposed to a vapor deposition target equipped with a patterned mask, and the vapor deposition layer is transferred by heating it. (See Patent Document 1). In addition, a method has been proposed in which an evaporation material is disposed on a patterned heating element to transfer the evaporation layer onto the substrate along the heating element (see Patent Document 2).

  By these methods, the distance between the vapor deposition source and the vapor deposition target can be made relatively short, so that the vapor deposition apparatus can be downsized and the material use efficiency can be improved even for a large area. Further, since the vapor deposition material is used up in one transfer, it is easy to ensure the reproducibility of the formed film thickness, and maintenance problems such as clogging of the crucible and deterioration of the vapor deposition material can be reduced.

Japanese Patent Laid-Open No. 11-54275 JP 2002-302759 A

  However, in the above conventional method, the vapor deposition source and the vapor deposition region have a one-to-one correspondence, and only a single layer film can be formed with one vapor deposition material support layer. In general, an organic EL element is formed of a multilayer film. However, in this method, it is necessary to exchange the vapor deposition material support layer every time a different layer is formed. There was a problem that would cause.

  An object of the present invention is to provide a vapor deposition method and a vapor deposition apparatus capable of forming a plurality of organic material layers in a lump without requiring exchange of a vapor deposition source for each layer.

  The vapor deposition method of the present invention is a vapor deposition method for forming a multilayer film composed of a plurality of organic material layers on a substrate having a plurality of pixels. The vapor deposition source group having a plurality of vapor deposition sources respectively corresponding to the plurality of pixels. A step of preparing each of the plurality of organic material layers, and a plurality of vapor deposition source groups prepared for each of the plurality of organic material layers supported in a space portion facing the plurality of pixels of the substrate. Filling the plurality of vapor deposition source groups supported in the space with different vapor deposition materials for each vapor deposition source group, while switching the vapor deposition source group for each layer of the plurality of organic material layers And a step of sequentially forming a plurality of organic material layers.

  The vapor deposition apparatus of the present invention is a vapor deposition apparatus for forming a multilayer film composed of a plurality of organic material layers on a substrate having a plurality of pixels, and a space portion facing the plurality of pixels of the substrate, and the plurality of organic For each layer of the material layer, a plurality of deposition source groups having a plurality of deposition sources respectively corresponding to the plurality of pixels, a support for supporting the plurality of deposition source groups in the space portion, and the plurality of the plurality of deposition sources A plurality of switchable heating elements each independently connected to the plurality of vapor deposition source groups in order to form the film while switching the vapor deposition source groups for each of the organic material layers. .

  By switching the plurality of vapor deposition source groups according to the film configuration of the organic multilayer film, the vapor of the vapor deposition material is released in order from each vapor deposition source group, thereby forming a multilayer film composed of a plurality of organic material layers without changing the vapor deposition source. It is possible to form a film in a lump. This eliminates the need for a deposition source exchange mechanism that is conventionally required for each organic material layer, and also eliminates the tact associated with the exchange.

  On the other hand, since the number of work steps when filling each vapor deposition source with the vapor deposition material is the same, there is no disadvantage in terms of the tact surface.

  The best mode for carrying out the present invention will be described with reference to the drawings.

  As shown in FIG. 1, for example, a metal block provided with a cylindrical hole is used as the evaporation source 110. The vapor deposition source 110 includes a plurality of vapor deposition source groups (groups) 111, 112, and 113, as will be described later, in the space facing the substrate transported to the vapor deposition apparatus, with openings in the same direction on a two-dimensional plane. Arranged to face. A plurality of vapor deposition sources 110 in each vapor deposition source group are filled with the same amount of the same material at regular distance intervals, and the vapor deposition source 110 is heated and controlled by the heating element 120 independently for each vapor deposition source group. A single layer film is formed. Heating is carried out until the material has evaporated more than 95%.

  Here, evaporating 95% or more corresponds to the film thickness to be formed being in the range of 95% to 100% of the designed value. This roughly corresponds to an error of the film thickness being within ± 2.5%. This is a value in a general range as a required value for optical design of the organic EL element.

Each vapor deposition source 110 faces and holds the distance between the vapor deposition source and the vapor deposition target so as to behave as a point source with respect to the vapor deposition target. Here, “behave as a point source” can be rephrased, for example, to follow the cosX power law of vapor deposition within an error range of ± 2.5%. The cosX power law means that when the vapor deposition source opening is oriented in the normal direction of the vapor deposition target surface, the film thickness at a position at an angle θ from the normal direction of the vapor deposition source follows [cos θ] ^{(3 + X)} . That's it. Thus, a single layer film can be obtained by vapor-depositing the same material using a plurality of vapor deposition sources.

  Such a plurality of groups of vapor deposition sources 110 are integrally supported by the support 130 in the same plane of the space facing the substrate, and a multilayer film made of a plurality of materials can be collectively formed. To do.

  In addition, for each vapor deposition source group, the shape and size of each vapor deposition source, and the arrangement interval are determined so that a uniform vapor deposition surface can be formed on the substrate to be vapor deposited. This can be determined by measuring the film thickness distribution of the organic material layer formed by a single vapor deposition source and simulating with a computer so that the overlap is a uniform film thickness. However, what can be determined here is the distance between each vapor deposition source and the ratio of the distance between the vapor deposition source and the substrate to be vapor deposited. When the distance between the deposition source and the substrate to be deposited is large, the influence of the radiant heat received by the mask and the vignetting effect by the mask is reduced, but the material is increased by increasing the outermost peripheral area where a uniform film thickness cannot be obtained. Usage efficiency decreases. It is desirable to determine the distance between the actual deposition sources and the distance between the deposition source and the substrate by balancing this.

The vapor deposition apparatus 100 in FIG. 1 includes a plurality of vapor deposition sources 110, a heating element 120, and a support 130. The material of the vapor deposition source 110 is preferably a material having a high thermal conductivity such as copper and a small specific heat, and the material of the heating element 120 is preferably a material obtained by slicing a refractory metal such as Mo. The dimensions can be appropriately determined according to the application. For example, as the vapor deposition source 110, as shown in FIG. 1A, a 1.2 × 1.2 × 2.0 mm ³ copper rectangular parallelepiped provided with a 1.0 mmφ × 1.5 mm hole, a heating element 120. As an example, a 50 μm-thick Mo thin film cut into a width of 1 mm can be used. The structure can also be appropriately determined according to the application, but a group of heating elements is set so that the vapor deposition sources 111, 112, 113 are in a square lattice pattern at equal intervals in a two-dimensional plane, and the vapor deposition material is selected accordingly. Fill each equal volume. That is, as shown in FIG. 1B, the heating element 120 is divided into three groups 121, 122, and 123 corresponding to the vapor deposition sources 111, 112, and 113 at equal intervals, and a different vapor deposition material is filled for each group. . And it heats and evaporates sequentially by the heat generating elements 121, 122, 123 controlled to be switched independently of each other. In this manner, by sequentially evaporating the vapor deposition material for each group, in the case of FIG. 1B, three layers of films can be sequentially and collectively formed.

  Further, as shown in FIG. 2A, a configuration using a unit 100a in which the vapor deposition source 110 is fixed to the heating element 120 at intervals of 4.5 cm and the heating elements 120 are arranged at intervals of 0.5 cm may be used. The vapor deposition source 110 is formed like a staple for a stapler and can be fixed by caulking to the heating element 120. Then, as shown in FIG. 2B, the plurality of units 100a are fixed to the support 130 so that the openings of the vapor deposition source 110 face the same direction.

  As an example, the experimental results of filling and evaporating an organic material in the vapor deposition source 110 of FIG. 2 will be described. In this case, the film thickness distribution can be well described by the cos 2.3 power law. FIG. 3 shows the measured film thickness distribution and the cos 2.3 power law calculation result when the distance between the vapor deposition source and the vapor deposition target is 14.0 mm.

  When vapor deposition sources conforming to the cos 2.3 power law are arranged in a square lattice at regular intervals, a uniform film is formed when the distance between the vapor deposition source and the vapor deposition target is 1.4 times the distance between the vapor deposition sources. (See FIG. 4).

  More specifically, as the distance from the deposition source increases, the periodic unevenness of the film thickness accompanying the periodicity of the deposition source decreases, but on the other hand, the ratio of the area where the uniform film on the outer periphery of the deposition source cannot be obtained increases. Resulting in. In the case where a variation of ± 1% is allowed as an influence of the periodic unevenness of the film thickness accompanying the periodicity of the vapor deposition source, the result of the calculation experiment is a condition for obtaining the maximum uniform film thickness region ratio in the configuration of the present invention. Can be formulated as follows.

  When following the cosX power law, the following relationship is established between the distance L between the vapor deposition source formed on the square lattice and the distance D from the vapor deposition source to the vapor deposition target substrate.

D / L = −0.005X ² + 0.141X + 1.075
By using a vapor deposition apparatus having such a configuration, a multilayer film can be collectively formed on a vapor deposition target that faces the vapor deposition source group in parallel.

  5A and 5B show an example of a multilayer organic film forming process and an organic EL panel mass production system using the vapor deposition method of the present invention. The system shown in FIG. 5B includes a chamber C1a for filling a deposition source with a material and storing a mask, a substrate stock chamber C1b, a substrate cleaning pretreatment chamber C1c, and a deposition chamber C2. Further, an EIL / Anode film forming chamber C3, a sealing chamber C4, a panel stock chamber C5, and the like are connected.

  As shown in FIG. 5A, the material filling into the vapor deposition source (step S101) is performed, for example, in the vapor deposition material filling / mask stock chamber C1a by distributing the material solution by ink-jetting or the solid material in the form of pellets. Distribution can be illustrated. In the case of dispensing by an ink jet method, it is desirable to perform pre-baking to remove the solvent. Thereafter, the vapor deposition source is transferred to the vapor deposition chamber C2 (step S102). In the case of distribution by the ink jet method, since it is necessary to transport from an atmospheric pressure to a vacuum atmosphere, it is necessary to provide a front chamber for evacuation. At this time, it is desirable to transport a plurality of vapor deposition sources all at once in a vacuum atmosphere in order to shorten tact time.

  As shown in FIG. 6, the distribution of the pellet-shaped solid material by the vapor deposition material distribution device D <b> 1 is more preferable because it can be easily conveyed by being performed in a vacuum atmosphere. Thereafter, in the vapor deposition chamber (deposition chamber) C2, the vapor deposition source driving device D2 is driven, and each organic material layer is formed on the substrate W by the heat generated by the heat generator (step S103). A plurality of organic material layers are formed for each pixel by sequentially heating the corresponding vapor deposition source group in accordance with the order of the organic material layers to be formed on the substrate W that has been aligned with respect to the mask M. Each organic layer single film is formed when each vapor deposition source is equal to or higher than the evaporation temperature of the material, and is completed when the vapor deposition material is used up. As for the heating timing of each vapor deposition source group, it is desirable to shorten the tact time so that the next organic material layer starts to be formed immediately after the immediately preceding organic material layer is formed. Thereafter, the vapor deposition source is carried out of the vapor deposition chamber C2 (step S104) and is again filled with the material. At this time, since all of the previously filled materials are skipped, no special regeneration process (maintenance) is required, but it is preferable to check the state of the vapor deposition source by checking organic residue using UV light.

  As shown in FIG. 2 (b), a 500 mm × 500 mm × 0.7 mm non-alkali glass plate is prepared as the support 130. 9 × 9 = 81 evaporation sources 110 and heating elements 120 each having the repeating unit 100a shown in FIG. 2A are arranged in the central area of 405 mm × 405 mm. The glass plate is provided with a 2 mm cylindrical opening corresponding to the portion where the vapor deposition source 110 is disposed. This is to prevent the heat of the heating element 120 from being taken away by the glass. Further, a non-alkali glass plate processed in the same manner is placed thereon, and the vapor deposition source 110 and the heating element 120 are fixed. The glass plate is fixed with screws.

The evaporation source is a 1.2 × 1.2 × 2.0 mm ³ copper rectangular parallelepiped with a 1.0 mmφ × 1.5 mm hole, and the heating element is a 50 μm thick Mo thin film cut to 1 mm width. . The vapor deposition source is fixed by forming one end like a staple for a stapler and caulking it to a heating element. Moreover, the opening part of a vapor deposition source is fixed so that it may face the same direction.

The heating elements are divided into nine groups (R, G, B) × (HTL, EML, ETL) shown in FIG. 2A, and each heating group is arranged in a square lattice at equal intervals of 4.5 cm. Consists of side-by-side vapor deposition sources. An equal amount of the same material is distributed to the vapor deposition sources belonging to each heat generation group. In this embodiment, the following amounts are distributed.
RHTL: α-NPD 80 μg
REML: CBP 60 μg / BtpIr (acac) 10 μg
RETL: BCP 100 μg
GHTL: α-NPD 80 μg
GEML: Alq3 30 μg / Coumarin 540 10 μg
GETL: BCP 100 μg
BHTL: α-NPD 80 μg
BEML: Alq3 30 μg / Perylene 10 μg
BETL: BCP 100 μg
Dispensing was performed by weighing each of the materials mixed at a specified ratio and preparing pellets of 0.3 to 0.4 mm square.

  A deposition target is placed at a location 63 mm away from the deposition source of the deposition apparatus. The evaporation target is a bottom emission type panel substrate that includes a TFT, is patterned with an ITO electrode as an anode, and an acrylic resin as an element isolation film, and includes 5 × 4 = 20 3 inch QVGA full color panels. The aperture sizes of the RGB pixels are the same and are regularly arranged at the same pitch.

  The mask is provided with an opening corresponding to any one color of RGB, and is aligned so that the opening corresponds to the vapor deposition portion of R to be vapor deposited.

  This is put in a vacuum vessel, and current is applied to each heat generating group in the order of RHTL → REML → RETL. The applied current is 9 A, and the application time is 20 seconds after the current / voltage is stabilized.

  The film thicknesses formed at this time are RHTL: 40 nm, REML: 35 nm, and RETL: 50 nm. Next, the mask opening is aligned with the pixel opening corresponding to G by shifting the mask. Thereafter, similarly, current is applied in the order of GHTL → GEML → GETL. The formed film thickness is GHTL: 40 nm, GEML: 20 nm, and GETL: 50 nm. The same operation is performed for B. The formed film thicknesses are BHTL: 40 nm, BEML: 20 nm, and BETL: 50 nm.

  Finally, the mask is replaced with an opening in the entire pixel display region, and LiF is formed on the entire surface of the 1 nm pixel display region using a movable evaporation crucible. Thereafter, Al is formed to 120 nm using a movable vapor deposition crucible.

  In this way, 20 sheets of 3 inch QVGA organic EL panels can be obtained.

The vapor deposition apparatus by one Embodiment is shown, (a) is the perspective view, (b) is the elements on larger scale which expand and show a part. The vapor deposition apparatus by another embodiment is shown, (a) is a figure explaining the structure of a 4.5cm square unit, (b) is a top view which shows the whole vapor deposition apparatus. It is a comparison of the film thickness distribution by a vapor deposition source and a cos rule. This shows a film thickness distribution formed on a vapor deposition target at a distance of 1.4 d from the vapor deposition source when 15 × 15 vapor deposition sources conforming to the cos 2.3 power law are arranged at intervals d. A solid graph representing the film thickness distribution three-dimensionally, (b) is a plane graph representing the film thickness distribution of (a) with contour lines. It is a figure which shows the film-forming process of a multilayer organic film, and an organic EL panel mass production system. It is a figure which shows the internal structure of a vapor deposition material filling and mask stock chamber of FIG. 5, and a vapor deposition chamber.

Explanation of symbols

100a Unit 110 Vapor Source 111-113 Vapor Source by Group 120 Heating Element 121-123 Heating Element by Group 130 Support

Claims (2)

In a vapor deposition method for forming a multilayer film composed of a plurality of organic material layers on a substrate having a plurality of pixels,
Preparing a deposition source group having a plurality of deposition sources respectively corresponding to the plurality of pixels for each of the plurality of organic material layers;
Supporting a plurality of vapor deposition source groups prepared for each of the plurality of organic material layers in a space portion facing the plurality of pixels of the substrate;
Filling the plurality of vapor deposition source groups supported in the space with different vapor deposition materials for each vapor deposition source group, and switching the vapor deposition source groups for each of the plurality of organic material layers, the plurality of organic materials And a step of sequentially forming the layers. In a vapor deposition apparatus for forming a multilayer film composed of a plurality of organic material layers on a substrate having a plurality of pixels,
A space portion facing the plurality of pixels of the substrate;
A plurality of vapor deposition source groups having a plurality of vapor deposition sources respectively corresponding to the plurality of pixels for each of the plurality of organic material layers;
A support for supporting the plurality of vapor deposition source groups in the space part;
A plurality of switchable heating elements each independently connected to the plurality of vapor deposition source groups in order to form a film while switching the vapor deposition source group for each of the plurality of organic material layers. A vapor deposition apparatus characterized.

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