Abstract:
A vapor deposition device for the vapor deposition of a substrate, and specifically particular of a substrate comprising heat-sensitive substances, for example OLEDs. To keep heat away from these substances, the vapor deposition device includes an evaporator tube with a special nozzle bar. This nozzle bar, which comprises several linearly arranged openings, projects with respect to the evaporator tube in the direction toward the substrate to be coated.

Description:
BACKGROUND AND SUMMARY OF THE INVENTION  
       [0001]     This application claims priority under 35 U.S.C. §119 from European Patent Application No. 050 16 365 filed Jul. 28, 2005, incorporated herein by reference in its entirety.  
         [0002]     The invention relates to a vapor deposition device.  
         [0003]     Modem flat-screen displays comprise liquid crystal elements (LCEs) or plasma elements for the rendering of images.  
         [0004]     Flat-screen displays have also recently been produced which utilize organic light-emitting diodes (OLEDs) as color pixels.  
         [0005]     Compared to the already known structural elements, a great advantage of the OLEDs is their high degree of efficiency of more than 16% (Helmuth Lemme: OLEDs—Senkrechtstarter aus Kunststoff, Elektronik 2/2000, p. 98. right column, 2nd paragraph, No. [5]: Yi He; Janicky, J.: High Efficiency Organic Polymer Light-Emitting Heterostructure Devices, Eurodisplay 99, VDE-Verlag Berlin, Offenbach). Therewith the OLEDs are situated far above the quantum efficiency of the LEDs comprised of inorganic III-V semiconductors.  
         [0006]     OLEDs, further, have lower weight, a wider angle of radiation, and produce colors of more intense brightness and can be applied in a broad temperature range from −40 C to 85 C. Of advantage is also that they can be operated at less than 5 Volts and have low electric energy consumption, which makes the OLEDs especially suitable for installation in battery-operated apparatus.  
         [0007]     The OLEDs can be produced by means of OVPD technology (OVPD=Organic Vapor Phase Deposition), such as is described in U.S. Pat. No. 5,554,220 or DE 101 28 091 C1. Therein the organic materials are applied onto an electrode located on glass. This electrode can be, for example, an ITO electrode (ITO=Indium Tin Oxide) which previously had been vapor deposited onto glass.  
         [0008]     Onto the OLED layer generated in this way further materials, in particular metal layers serving as counterelectrodes, can be applied or vapor deposited. Devices for vaporizing metals are known as such (EP 0 477 474 B1, JP 10008241 A1, DE 976 068, U.S. Pat. No. 4,880,960).  
         [0009]     In an evaporator device for vaporizing metals which are utilized in the production of OLED flat-screen displays, an evaporator housing is placed perpendicularly onto the crucible (DE 102 56 038 A1). This evaporator device, as does the evaporator device according to DE 101 28 091 A1 also, includes a linear distributor system. In this linear distributor system several evaporator apertures are arranged linearly. The metal vapor escaping through these apertures impinges onto a substrate located parallel to the evaporator apertures.  
         [0010]     In the evaporator device according to DE 102 56 038 A1 the thermal insulation is interrupted in the proximity of the outlet apertures for the vapor, as a consequence of which the evaporator tube is colder at this site than at those sites at which the evaporator tube is encompassed by the insulation. This interruption of the thermal insulation leads to the fact that the substrates are subjected to strong thermal loading on the part of the evaporator tube. For, while the evaporator tube becomes relatively cool in the proximity of the outlet apertures, it is still very hot and radiates heat onto the substrate.  
         [0011]     To shield the substrate, at least to some extent, against the heat radiated in the proximity of the outlet apertures, retroreflective metal sheeting is provided in the known device.  
         [0012]     Lastly, an evaporator device is also known with which the vaporized material can be deposited over a mask onto a plate (JP 2004-214185). This evaporator device comprises an evaporator crucible in which material is vaporized. In the upper region of the crucible is a projecting part directed toward the plate. In the projecting part an opening is provided, and specifically in the direction from the interior of the crucible toward the plate. About the projecting part a shielding is provided located at the same or lower level than the opening and spaced apart from the upper surface of the crucible. It is not possible with this evaporator device to coat flat substrates oriented parallel to the gravitational force of the earth, such as for example glass plates, since the evaporator stream or the evaporator directional lobe is emitted parallel to the direction of the earth&#39;s gravitational force.  
         [0013]     The aim of the invention is to decrease the thermal loading even of such flat substrates whose surface is oriented parallel to the gravitational force of the earth.  
         [0014]     This aim is attained with a device according to the present invention.  
         [0015]     The invention consequently relates to a vapor deposition device for the vapor deposition of a substrate, and specifically of a substrate which contains heat-sensitive substances, for example OLEDs. To keep heat away from these substances, the vapor deposition device includes an evaporator tube with a special nozzle bar. This nozzle bar, which includes several linearly arranged openings, relative to the evaporator tube projects in the direction toward the substrate to be coated.  
         [0016]     The advantage attained with the invention comprises in particular that the nozzle bar precedes the evaporator tube in such formation that it is possible to insulate the tube up to the nozzle bar leading to a reduction of the heat-radiating area. Due to this improved insulation the substrate is significantly better protected against the radiated heat, such that also heat-sensitive substances, such as for example OLEDs, can be coated with metals.  
         [0017]     Embodiment examples of the invention are depicted in the drawing and will be described in further detail in the following. 
     
    
     BRIEF DESCRIPTION OF THE FIGURES  
       [0018]      FIG. 1  is a perspective overall view of a vapor deposition device.  
         [0019]      FIG. 2  shows a partially sectioned vapor deposition device.  
         [0020]      FIG. 3  shows a longitudinal section through the vapor deposition device according to  FIG. 1 .  
         [0021]      FIG. 4  is an enlarged cut-out from  FIG. 2 .  
         [0022]      FIG. 5  shows a nozzle bar with tapering cone-shaped nozzles forwardly located.  
         [0023]      FIG. 6  shows a cut-out of a portion of the evaporator tube with the nozzle bar according to  FIG. 5 . 
     
    
     DETAILED DESCRIPTION  
       [0024]      FIG. 1  depicts a perspective overall view of a vapor deposition device  1  comprising an upper part  2  and a lower part  3 . Both parts  2 ,  3  are held together by an upper and a lower connection clamp  4 ,  5  as well as by a bolt  6 . Several such connection clamps and bolts may be provided over the circumference of the vapor deposition device  1 .  
         [0025]     On the top side  7  of the upper part  2  an inlet tube  8  is indicated. By  9  and  10  are denoted cooling means ports, which are also located on the top side of the upper part  2 .  
         [0026]     Further cooling means ports  11 ,  12  are located on the lower part  3 .  
         [0027]     The vapor deposition device  1  stands perpendicularly, i.e. parallel to the direction of the gravitational force of the earth. A substrate  13  to be coated, for example a glass plate coated with OLED, is guided past the vapor deposition device  1 , and specifically horizontally, as indicated by arrow  14 . The OLED may be disposed on an ITO layer, which forms a first electrode. The metal layer now to be vapor deposited in this case forms, for example, the second electrode.  
         [0028]     In the upper part  2  of the vapor deposition device opposite the substrate  13  is a vertically disposed gap  15  through which coating material reaches the surface of the substrate  13 . Consequently, the coating material reaches the surface of substrate  13  linearly and perpendicularly.  
         [0029]      FIG. 2  shows again the upper part  2  of the vapor deposition device  1  in a partially sectioned illustration. Through the section A-A parallel to the footprint, the internal structure of the upper part  2  can be seen.  
         [0030]     Compared to the illustration of  FIG. 1 , the upper part  2  is rotated about 90 degrees, such that details of the gap  15  can be seen. The rotation takes place in the direction of arrow  16  ( FIG. 1 ) i.e. in the counterclockwise direction.  
         [0031]     In this upper part  2  an interior evaporator tube  17  at a site of its circumference is provided with an outwardly projecting nozzle bar  18 . This nozzle bar  18  has two flanks  27 ,  28 , which project from the circumference and are connected at their ends through a web  21 . In this web  21  are disposed linearly above one another several openings  22  extending over the entire length of the nozzle bar  18 .  
         [0032]     About the evaporator tube  17  is placed an insulating layer  26 , comprised, for example, of a graphite felt or special ceramics, which is carried up to the front edges  19 ,  20  of the nozzle bar  18 . About the insulating layer  26 , which must withstand temperatures up to 1,700° C., is placed a tubular shielding  29 , for example of metal, which, in turn, is encompassed by a double-walled tube, preferably of metal, whose walls  30  and  31  are connected with one another through webs  32 ,  33 . Between these webs  32 ,  33  a cooling means, for example water, may flow, i.e. the webs  32 ,  33  form cooling means channels. The insulating layer  26 , the shielding  29 , and the double-walled tube have cutouts forming a recess at the site at which the nozzle bar  18  is located.  
         [0033]     The nozzle bar  18  has very good thermal conductivity, which corresponds at least to the thermal conductivity of the evaporator tube  17 .  
         [0034]     Since the insulating layer  26  reaches to the front edges  19 ,  20  of the nozzle bar  18 , the remaining evaporator tube is completely encompassed by the insulating layer, such that no heat can be radiated in the direction onto the substrate. Consequently, the heat radiated onto the substrate originates solely from the nozzle bar  18 . However, this bar must be so hot that no condensation of the vapor takes place.  
         [0035]      FIG. 3  shows a longitudinal section B-B through the vapor deposition device  1  according to  FIG. 1 . Herein the evaporator tube  17  can be seen seated on a crucible  35 . The crucible  35  comprises at its upper end a flaring  36 , while the evaporator tube  17  has a taper  37  at its lower end. This taper  37  rests on the flaring  36 .  
         [0036]     The flank  27  and the web  21  with the openings  22  of the nozzle bar  18  are shown to the left of the center of the evaporator tube  17 .  
         [0037]     By  40  is denoted a heating system for the crucible  35 , which encompasses the crucible  35 . This heating system  40  is encompassed by a shielding  41 , which, in turn, is encompassed by a cooling system  42 . A supply line for electrical energy is schematically denoted by  43 .  
         [0038]      FIG. 4  shows an enlarged cut-out representation of  FIG. 3 . It is clearly evident that the insulating layer  26  is carried up to the front edges  19 ,  20  of the nozzle bar  18 . It is additionally evident that the nozzle bar  18  can be comprised of a material different from that of the evaporator tube  17 . Its flanks  27 ,  28  are adapted to the open ends of the evaporator tube  17 .  
         [0039]      FIG. 5  shows a cut-out of another nozzle bar  50  in which, in comparison with the nozzle bar  18 , the openings  51  to  55  are located forwardly. These openings  51  to  55  form the end of outwardly tapering cones  56  to  60 , which are disposed on the nozzle bar  18 . By  61 ,  62  are denoted the bores for the heating filaments. With such heating filaments the nozzle bar  18  can be heated independently of the evaporator tube  17 .  
         [0040]     If such a nozzle bar  50  with forwardly located nozzles is installed into an evaporator tube, it is possible to place insulating material over the cones  56  to  60 .  
         [0041]      FIG. 6  shows the manner in which the cones  56  to  60  of the nozzle bar  50  are embedded in the insulating material. Consequently, the entire nozzle bar  50  is practically embedded in insulating material  26 . Only the ends of the cones  56  to  60  are still capable of radiating heat.  
         [0042]     The evaporator tube depicted in FIGS.  1  to  6  is always shown as a cylindrical tube. However, it is understood that it may also have the cross section of an n-gon and the sides may be equal or unequal. For example, it may have a rectangular, in particular square, cross section.  
         [0043]     In all cases it makes possible a compact evaporator source, whose length—unlike in JP 2004-214185—does not need to correspond to the length of the evaporator bar.