Abstract:
A method of forming a pattern includes: providing a heating substrate that selectively controls positions where heat is generated by controlling locations where electric current flows; forming a pattern forming material on a surface of the heating substrate; aligning a patterning substrate, on which a pattern may be formed, to face a surface of the heating substrate; and selectively applying electric current to the heating substrate to transfer some of the pattern forming material onto the patterning substrate. According to the method of forming the pattern and a method of fabricating an OLED, the pattern is transferred by heating the pattern forming material formed on the heating substrate, and thus, the pattern may be formed with high accuracy without using a mask, and the pattern forming material remaining on the heating substrate may be re-used.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefit of Korean Patent Application No. 10-2009-0132824, filed Dec. 29, 2009 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference. 
       BACKGROUND 
       [0002]    1. Field 
         [0003]    One or more embodiments of the present invention relate to a method of forming patterns and a method of manufacturing an organic light emitting device, and more particularly, to a method of forming patterns by using electric resistance heat generating on a heating substrate, and a method of manufacturing an organic light emitting device. 
         [0004]    2. Description of the Related Art 
         [0005]    Electroluminescence devices are self-emissive display devices and are considered as a next generation display device because of excellent characteristics thereof. For example, electroluminescence devices have an excellent wide viewing angle, high contrast, and fast response speed. 
         [0006]    Electroluminescent devices may be classified as inorganic electroluminescent devices and organic electroluminescent devices according to a material forming a light emission layer. In organic electroluminescent devices, an organic light emitting material is deposited in a vacuum atmosphere by using a mask having a predetermined pattern in order to form an organic layer. When patterning the organic layer using the mask, the technology of patterning the organic layer that is the light emission layer is very important in the entire processes of manufacturing full-color organic electroluminescent devices. 
         [0007]    In the manufacturing process of the organic electroluminescent device, a large substrate is generally used to manufacture many organic electroluminescent devices through a one-time process. Also, as a demand for a large display increases, the size of a display itself increases as well. However, since the large substrate sags due to the gravity in the deposition process as the size thereof increases, it is difficult to increase a degree of precision of a pattern when the organic light emitting material is deposited by using the mask. 
       SUMMARY 
       [0008]    One or more embodiments of the present invention include a method of forming a pattern which may form a pattern with high precision by transferring a pattern forming material using a heating substrate to remove a sagging phenomenon of the substrate, which may be generated when the pattern is formed on a large size substrate, and a method of manufacturing an organic light emitting device. 
         [0009]    One or more embodiments of the present invention include a method of forming a pattern which may be suitable for forming a pattern on a large substrate, and a method of manufacturing an organic light emitting device. 
         [0010]    According to one or more embodiments of the present invention, a method of forming a pattern, the method includes: providing a heating substrate that selectively controls positions where heat is generated by controlling locations where electric current flows; forming a pattern forming material on a surface of the heating substrate; aligning a patterning substrate, on which a pattern may be formed, to face a surface of the heating substrate; and selectively applying electric current to the heating substrate to transfer some of the pattern forming material onto the patterning substrate. 
         [0011]    According to one or more embodiments of the present invention, a method of fabricating an organic light emitting device (OLED), the method includes: providing a heating substrate that selectively controls positions where heat is generated by controlling locations where electric current flows; forming a pattern forming material on a surface of the heating substrate; aligning a patterning substrate, on which a plurality of pixel electrodes are formed, to face a surface of the heating substrate; and selectively applying electric current to the heating substrate to transfer some of the pattern forming material onto the patterning substrate. 
         [0012]    Other aspects, features, and advantages of the embodiments of the present invention will be clear from drawings, claims, and detailed description of the invention. 
         [0013]    According to embodiments of the present invention, the pattern is transferred by heating the pattern forming material formed on the heating substrate, and thus, the pattern may be formed on the large substrate with high accuracy without using a mask. In addition, the pattern forming material remaining on the heating substrate after the process may be re-used. 
         [0014]    Additional aspects and/or advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]    These and/or other aspects and advantages of the invention will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which: 
           [0016]      FIG. 1  is a flowchart illustrating a method of forming patterns according to an embodiment of the present invention; and 
           [0017]      FIGS. 2 through 7  are diagrams illustrating processes of forming patterns according to an embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0018]    Reference will now be made in detail to the present embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. The embodiments are described below in order to explain the present invention by referring to the figures. 
         [0019]    The terms used in the present specification are used for explaining a specific exemplary embodiment, not limiting the present inventive concept. Thus, the expression of singularity in the present specification includes the expression of plurality unless clearly specified otherwise in context. Also, the terms such as “include” or “comprise” may be construed to denote a certain characteristic, number, step, operation, constituent element, or a combination thereof, but may not be construed to exclude the existence of or a possibility of addition of one or more other characteristics, numbers, steps, operations, constituent elements, or combinations thereof. 
         [0020]    The method of forming a pattern and the method of manufacturing an organic light emitting device according to the present invention will be described in detail with reference to  FIGS. 1 through 7 .  FIG. 1  is a flowchart illustrating the method of forming a pattern according to an embodiment of the present invention, and  FIGS. 2 through 7  are flow diagrams illustrating the method of forming a pattern according to an embodiment of the present invention. 
         [0021]    Referring to  FIGS. 1 and 2 , a heating substrate  10  is prepared in operation S 100 . Here, the heating substrate  10  generates heat according to flow of electric current, and may control the generated heat by controlling the flow of electric current. While not required in all aspects, as shown in  FIG. 2 , the heating substrate  10  is formed by coupling a plurality of electric heating lines  12  onto a substrate  11 . The electric heating lines  12  may be attached to the substrate  11 , wound on the substrate  11 , or may be embedded in the substrate  11 . The substrate  11  may be formed of a glass material or an insulating material. In addition, the electric heating lines  12  may be formed of an alloy of iron (Fe) and chromium (Cr) or an alloy of nickel (Ni) and Cr, which generates the heat by the flow of the electric current and an electrical resistance of the heating lines  12 . The electric current respectively flows in each of the plurality of electric heating lines  12 , and the flow of electric current may be controlled by a selection of a user manufacturing organic light emitting device. While described in terms of using electrical resistance to provide heat, it is understood that the lines  12  could generate or transfer heat using other mechanisms. For instance, the lines  12  could generate heat using as chemical reactions, transport heated materials within the lines  12 , conduct from a heat source, and/or use other electrical mechanisms usable to generate heat such as induction. 
         [0022]    The position where the current flows may be selectively controlled due to the structure of the heating substrate  10 . Accordingly, the electric resistance heat generated in the heating substrate  10  may be selectively generated at a position corresponding to the current flowing position. The magnitude of the heat generated in the heating substrate  10  may be adjusted according to the thickness of the electric heating lines  12  coupled to the heating substrate  10  or the amount of current flowing through the electric heating lines  12 . That is, as the electric heating lines  12  are designed to be thicker or the amount of current flowing through the electric heating lines  12  increases, the magnitude of the electric resistance heat selectively generated in the heating substrate  10  may be increased. When the heating substrate  10  of large area is used, the thicknesses of the electric heating lines  12  may vary according to locations thereof or resistances of the electric heating lines  12  may be differentiated from each other in order to control the temperature of the heat generated on a front surface of the substrate to be constant. As shown, the heating lines  12  are parallel lines, but it is understood that the lines  12  can be non-linear, need not be continuous, and need not be parallel in all aspects. 
         [0023]    The pattern of the electric heating lines  12  may be formed in relation to a pattern to be formed on a patterning substrate  20  which will be described later. 
         [0024]    Next, as shown in  FIGS. 1 and 3 , a pattern forming material  40  is deposited on a surface of the heating substrate  10  in operation S 200 . The pattern forming material is transferred on a surface of the patterning substrate  20  to form a pattern in a patterning process that will be described later. The pattern forming material  40  of the present embodiment is an organic compound which may form an organic light emitting layer on the patterning substrate formed of low temperature poly-silicon in order to fabricate an organic light emitting device (OLED). In particular, a material emitting one of red, green, and blue colors may be used in order to emit color lights from the OLED. The color of the light emitted from the OLED may be determined according to the selected organic compound. 
         [0025]    The pattern forming material  40  may be provided on a surface of the heating substrate  10  in a deposition method or a sputtering method. That is, the pattern forming material  40  is vacuum-deposited or sputtered on the surface of the heating substrate  10 , and thus, the pattern forming material  40  may be applied on the entire surface of the heating substrate  10 .  FIG. 3  shows that the pattern forming material  40  applied on the surface of the heating substrate  10  in the depositing or sputtering method. However, it is understood that other mechanisms can be used to apply the pattern forming material  40 , such as spin coating. 
         [0026]    In addition, as shown in  FIGS. 1 and 4 , the patterning substrate  20  for forming the pattern is aligned to face the surface of the heating substrate  10 , on which the pattern forming material  40  is stacked in operation S 300 . According to an embodiment of the present invention, the patterning substrate  20  may be a low temperature poly-silicon (LTPS) substrate that may be used to manufacture the OLED. In the shown embodiment, the LTPS substrate is a large substrate in which a plurality of OLEDs may be formed and is the patterning substrate  20  where a pattern layer of an organic compound is formed by a below-described process. 
         [0027]      FIG. 5  shows the patterning substrate  20  in detail according to an embodiment of the present invention. An organic light emitting layer is patterned on a pixel electrode  60  so that an active matrix (AM) type OLED may be fabricated by using the patterning substrate  20 . According to the embodiment of the present invention, the patterning substrate  20  may have a structure, in which a buffer insulating layer  22  is stacked on a glass substrate  21 . An active layer  23  is formed on the buffer insulating layer  22 . A gate insulating  24  covers the active layer  23 . The active layer  23  may have a poly-si structure after a-si is deposited and then a crystallization process is performed. 
         [0028]    In addition, a gate electrode  25  is formed on the gate insulating layer  24 , an interlayer dielectric  26  is stacked on the gate electrode, and then a drain electrode  27  and a source electrode  28  are formed on the interlayer dielectric  26 . The drain electrode  27  and the source electrode  28  contact the active layer  23  by penetrating through the interlayer dielectric  26 , and may be covered by a passivation layer  29 . Here, the drain electrode  27  is connected to the pixel electrode  60  that is formed on the passivation layer  29  so as to transfer an output voltage of a thin film transistor (TFT) to the pixel electrode  60 . 
         [0029]    In addition, a pixel definition layer  61  is formed on top of the stacked substrate to have the pixel electrode  60  exposed. An organic light emitting layer is patterned on the exposed pixel electrode  60 . After the organic light emitting layer is patterned, a second electrode (not shown) is formed on the organic light emitting layer in a direction to cross the pixel electrode  60 , thereby completing the OLED. In the shown embodiment, as illustrated in  FIG. 5 , the patterning substrate  20  is used in a state before the organic light emitting layer is patterned, and the organic light emitting layer may be formed on the pixel electrode  60  that is opened, in a pattern forming process that will be described later. 
         [0030]    The patterning substrate  20  is aligned on a surface of the heating substrate  10 , as illustrated in  FIG. 4 . The heating substrate  10  is aligned to correspond to a position of a pattern to be formed on the patterning substrate  20 , and also, so that the pattern forming material that is vaporized by the heat generated from the heating substrate  10  may be deposited again on the patterning substrate  20  to form the pattern on the patterning substrate  20 . 
         [0031]    Then, as illustrated in  FIG. 6 , current is selectively applied to the heating substrate  10  to transfer some of the pattern forming material  40  attached on the heating substrate  10  onto the patterning substrate  20 . In a state in which the patterning substrate  20  and the heating substrate  10  are aligned, as current is selectively applied to the heating substrate  10 , an electric resistant heat is generated only at positions A corresponding to the position where the current flows through the heating lines  12  as illustrated in  FIG. 6 . The pattern forming material  40  is locally heated on the portions where the heat is generated in the heating substrate  10 . Accordingly, the pattern forming material  40  is vaporized and deposited on the pattern substrate  20  again. The deposited pattern forming material  40  is transferred to the patterning substrate  20  at the desired positions to form the pattern (that is, the pattern of the organic light emitting layer) without depositing the pattern at other positions for other colors. 
         [0032]    Thus, the pattern of the electric heating lines  12  may correspond to the pattern that is to be formed on the patterning substrate  20 . That is, the electric heating lines  12  may be formed as a pattern that may generate the heat on the location of the pattern that will be formed on the patterning substrate  20 . Further, the lines  12  can be selectively used so as to only deposit specific patterns. 
         [0033]    The processes illustrated in  FIGS. 2 through 6  are repeatedly performed to transfer the pattern  50  selectively onto the desired positions of the patterning substrate  20  as shown in  FIG. 7 , and the material forming the pattern may be selected. 
         [0034]    When one of red, green, and blue light emitting layers of the OLED is formed in the above method, the electric heating lines  12  are formed in a pattern corresponding to all red, green, and blue pixels. Then, to form a red light emitting layer, an electric current is applied to the electric heating lines  12  corresponding to the red pixels to deposit the red pattern forming material. Also, to form a green light emitting layer, an electric current is applied to the electric heating lines  12  corresponding to the green pixels to deposit the green pattern forming material. To form a blue light emitting layer, an electric current is applied to the electric heating lines  12  corresponding to the blue pixels to deposit the blue pattern forming material. While not described, it is understood that, after each pattern is formed, the pattern forming material  40  is exchanged for another material forming another color. As a result, the red, green, and blue light emitting layers may be sequentially formed. 
         [0035]    In the above description of the embodiment of the present invention, the process for forming the pattern  50  of an organic layer needed for manufacturing an OLED is described. In manufacturing the OLED, since the organic layer is very weak to moisture, the organic layer should be completely isolated from moisture during and after the manufacturing process. Accordingly, a photolithography method in which the organic layer is exposed to moisture in a resist separation process and an etching process is not suitable for the process for forming an organic layer pattern. Thus, the embodiments of the present invention may be effectively employed for manufacturing a large OLED because the organic layer is patterned without contact of moisture and a mask sagging phenomenon is removed. 
         [0036]    The above-described pattern forming process may be applied in various ways to the pattern forming process in which a wet process is difficult to employ. That is, the embodiments of the present invention may be employed in a process for forming a circuit pattern of a printed circuit board by using a conductive pattern forming material to the patterning substrate formed of an insulation material. Also, the embodiments of the present invention may be employed to a process for forming a pattern by using a mask in a deposition or sputtering method. 
         [0037]    Although a few embodiments of the present invention have been shown and described, it would be appreciated by those skilled in the art that changes may be made in this embodiment without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents.