Abstract:
An organic light emitting display is capable of preventing or reducing a scratch and a short between the wire lines due to the scratch. The organic light emitting display includes a pixel substrate including an organic light emitting element formed on a pixel region and wire lines formed in a surrounding area of the pixel region; and a protrusion formed between the wire lines.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefit of Korean Application No. 2007-24622, filed Mar. 13, 2007 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    Aspects of the present invention relate to an organic light emitting display, and more particularly, to an organic light emitting display and a method of manufacturing the same to prevent or reduce a scratch on wire lines thereof. 
         [0004]    2. Description of the Related Art 
         [0005]    An organic light emitting display is a self-emitting display that uses a phenomenon in which electrons and holes injected into an organic material through an anode and a cathode, respectively, are recombined to form excitons. The excitons thereby generate a light beam with a specific wavelength by releasing energy. The organic light emitting display does not require a separate light source, such as a backlight, resulting in low or lower power consumption. Furthermore, since a wide viewing angle and a fast response time of the organic light emitting display can be easily ensured, the organic light emitting display is expected to be a next generation display. 
         [0006]    In terms of a driving method, the organic light emitting display is classified into a passive matrix type and an active matrix type. In recent years, the active matrix type organic light emitting display has become more prevalent over the passive matrix type organic light emitting display. The active matrix type organic light emitting display enables realization of low power consumption, high definition, fast response time, wide viewing angle, and light thin film characteristics. 
         [0007]    In an active matrix type organic light emitting display, a pixel region is formed on a pixel substrate so as to display an image. Also, wire lines, and data and scan drivers to operate the pixel region using signals input through pads of the wire lines, are formed in a surrounding area of the pixel region. Pixels in the pixel region, each of which is a basic unit for image display, are arranged in a matrix form, and an organic light emitting element is disposed for each pixel. The organic light emitting element includes a first pixel electrode of a positive polarity and a second pixel electrode of a negative polarity that are sequentially formed with an emitting layer interposed therebetween. The emitting layer includes a red (R), green (G), and/or blue (B) organic material. A thin film transistor (TFT) is in contact with the organic light emitting element so that the each pixel can be separately controlled. 
         [0008]    The pixel substrate of the organic light emitting display is sealed by a sealing substrate to protect the pixels. Although the organic light emitting display is sealed, the wire lines and the pads are not sealed in order to be used to input external signals. Accordingly, the wire lines and the pads may be easily damaged by an external physical impact. In particular, a scratch may be produced on the wire lines as shown in  FIGS. 5A to 5C  to cause a short between the wire lines so that driving of the pixel deteriorates. 
       SUMMARY OF THE INVENTION 
       [0009]    Aspects of the present invention provides an organic light emitting display capable of preventing or reducing a scratch on wire lines and a short between the wire lines due to the scratch and other advantages. 
         [0010]    According to an aspect of the present invention, an organic light emitting display includes: a pixel substrate including an organic light emitting element formed on a pixel region and wire lines formed in a surrounding area of the pixel region; and a protrusion formed between the wire lines. 
         [0011]    In the above aspect of the present invention, the protrusion may be made of a material having a Mohs hardness that is larger than that of the wire lines. For example the protrusion may be made of silicon nitride and/or silicon oxide. 
         [0012]    In addition, the organic light emitting element may have a first pixel electrode, an organic light emitting layer, and a second pixel electrode that are sequentially stacked. The organic light emitting display may further include a sealing substrate formed on the pixel substrate to protect the pixel region. 
         [0013]    According to another aspect of the present invention, an organic light emitting display includes: a thin film transistor which is formed on a pixel region of a pixel substrate and includes an active layer, a gate insulating layer formed on a first surface of the pixel substrate to cover the active layer, a gate electrode formed on the gate insulating layer, an interlayer insulating layer formed on the gate insulating layer to cover the gate electrode, and source and drain electrodes formed on the interlayer insulating layer; a planarization layer to cover the thin film transistor and is formed on the interlayer insulating layer; an organic light emitting element formed on the planarization layer; and wire lines formed in a surrounding area of the pixel region, wherein a concave portion is formed in the interlayer insulating layer in the surrounding area of the pixel region, and the wire lines are disposed in the concave portion. 
         [0014]    In the above aspect of the present invention, the wire lines may have a height that is lower than that of a surface of the interlayer insulating layer. For example, the interlayer insulating layer may be made of silicon nitride and/or silicon oxide 
         [0015]    In addition, a concave portion may be formed in the gate insulating layer disposed under the concave portion of the interlayer insulating layer. The planarization layer may fill the concave portion. The organic light emitting element may have a first pixel electrode, an organic light emitting layer, and a second pixel electrode that are sequentially stacked. The organic light emitting display may further include a sealing substrate formed on the pixel substrate to protect the pixel region. 
         [0016]    According to another aspect of the present invention, a method of manufacturing an organic light emitting display includes: forming an active layer of a pixel region on a pixel substrate; forming a gate insulating layer on a first surface of the pixel substrate to cover the active layer; forming a gate electrode on the gate insulating layer; forming an interlayer insulating layer on the gate insulating layer to cover the gate electrode; forming first and second contact holes to expose the active layer on the pixel region by patterning the interlayer insulating layer and the gate insulating layer and to simultaneously form a concave portion in a surrounding area of the pixel region; forming source and drain electrodes that are electrically connected to the active layer through the first and second contact holes on the interlayer insulating layer and simultaneously forming wire lines in the concave portion; forming a planarization layer on the interlayer insulating layer to fill the concave portion; and forming an organic light emitting element on the planarization layer. 
         [0017]    The wire lines may have a height that is lower than that of a surface of the interlayer insulating layer. The interlayer insulating layer may be made of silicon nitride and/or silicon oxide. The organic light emitting element may have a first pixel electrode, an organic light emitting layer, and a second pixel electrode that are sequentially stacked. 
         [0018]    According to another aspect of the present invention, an organic light emitting display includes a pixel substrate including a pixel region of a plurality of pixels; a plurality of trenches formed on the pixel substrate around a periphery of the pixel region; and a plurality of wire lines each formed in a corresponding one of the plurality of trenches. 
         [0019]    According to another aspect of the present invention, a method of forming an organic light emitting display, includes forming a pixel substrate to include a pixel region of a plurality of pixels; forming a plurality of trenches on the pixel substrate around a periphery of the pixel region; and forming a plurality of wire lines in a corresponding one of the plurality of trenches. 
         [0020]    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 
         [0021]    These and/or other aspects and advantages of the invention will become apparent and more readily appreciated from the following description of the aspects, taken in conjunction with the accompanying drawings of which: 
           [0022]      FIG. 1  is a top plan view showing an organic light emitting display according to aspects of the present invention; 
           [0023]      FIG. 2  is a cross-sectional view taken along lines II A-II A′ and  11  B-II B′ of an organic light emitting display according to one aspect of  FIG. 1 ; 
           [0024]      FIG. 3  is a cross-sectional view taken along line II A-II A′ and II B-II B′ of an organic light emitting display according to another aspect of  FIG. 1 ; 
           [0025]      FIGS. 4A ,  4 B, and  4 C are process views to explain a method of manufacturing an organic light emitting display according to an aspect of the present invention; and 
           [0026]      FIGS. 5A ,  5 B, and  5 C are views showing a scratch on wire lines of a related organic light emitting display, in which  FIG. 5A  is a microscope image,  FIG. 5B  is a focused ion beam (FIB) image, and  FIG. 5C  is a partially enlarged image of  FIG. 5B . 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0027]    Reference will now be made in detail to the aspects of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. The aspects are described below in order to explain the present invention by referring to the figures. 
         [0028]    In the figures, the dimensions of layers and regions may be exaggerated for clarity. It will also be understood that when a layer or element is referred to as being “on” or “over” another layer or substrate, it can be directly on the other layer or substrate, or intervening layers may also be present. Further, it will be understood that when a layer is referred to as being “under” or “below” another layer, it can be directly under, or one or more intervening layers may also be present. 
         [0029]    First, an organic light emitting display according to an aspect of the present invention will be described with reference to  FIGS. 1 and 2 . Referring to  FIG. 1 , the organic light emitting display includes a pixel substrate  100 , a pixel region  110  formed on the pixel substrate  100  to display an image, and pixels  111 , each of which is a basic unit in displaying the image. The pixel region  110  and the pixels  111  are arranged in a matrix form. 
         [0030]    In a surrounding area of the pixel region  110 , the organic light emitting display further includes wire lines  253  having pads  160 , a scan driver  120  and a data driver  130  connected to the wire lines  253  to drive the pixel region  110  by way of signals input through the pads  160 , a power source line  140  to supply a power source voltage to the pixels  111  of the pixel region  110 , and a second pixel electrode wire line  254  to supply an anode voltage to a second pixel electrode  340 , which will be described later. In the aspect shown, the second pixel electrode  340  contacts the second pixel electrode wire line  254  through a via hole  323 . The second pixel electrode  340  is formed on the entire pixel region  110  to supply the anode voltage to a plurality of the pixels  111  arranged in the pixel region  110 . In addition, as shown in  FIG. 1 , the second pixel electrode  340  may be formed even on the scan driver  120  and data driver  130 . 
         [0031]    In the aspect shown, the pixel  111  includes a switching first thin film transistor (TFT) T 1 , a driving second TFT T 2 , a storage capacitor Cst, and an organic light emitting element L 1 , but is not limited thereto. For example, the pixel  111  may include two or more switching TFTs, driving TFTs, storage capacitors, and/or other elements. 
         [0032]    The first TFT T 1  is connected to a scan line SL 1  and a data line DL 1 , respectively. The first TFT Ti transmits a data voltage that is input through the data line DL 1  to the second TFT T 2  according to the switching voltage that is input through the scan line SL 1 . The storage capacitor Cst is connected to the first TFT T 1  and the power source line VDD, respectively. The storage capacitor Cst stores a voltage V gs  corresponding to a difference between a voltage transmitted from the first TFT T 1  and a voltage supplied to the power source line VDD. 
         [0033]    The second TFT T 2  is connected to the power source line VDD and the storage capacitor Cst, respectively. The second TFT T 2  supplies an output current I d  to the organic light emitting element L 1 , which is proportionate to a square of a difference between the voltage stored in the storage capacitor Cst and a threshold voltage V th . The organic light emitting element L 1  emits light by way of the output current I d . In the aspect shown, the output current I d  can be represented by the following Equation 1, in which β denotes a proportionality constant. 
         [0000]        I   d =(β/2)×( V   gs   −V   th ) 2    [Equation 1] 
         [0034]    Referring to  FIG. 1 , a sealing substrate  400  is formed on the pixel substrate  100  to protect the pixel region  110 . 
         [0035]      FIG. 2  is a cross-sectional view taken along lines II A-II A′ and II B-II B′ of an organic light emitting display according to one aspect of  FIG. 1 . Referring to  FIG. 2 , the structure of the pixels  111  on the pixel substrate  100  and of the wire lines  253  will be described in detail. As shown, a buffer layer  200  is formed on the substrate  100 . Formed on the buffer layer  200  is an active layer  210  that includes source and drain regions  211  and  212 , and a channel region  213  interposed therebetween. A gate insulting layer  220  is formed on the buffer layer  200  to cover the active layer  210 , and a gate electrode  230  is formed on the gate insulating layer  220  on the active layer  210 . An interlayer insulating layer  240  is formed on the gate insulating layer  220  to cover the gate electrode  230 . In the interlayer insulating layer  240 , a source electrode  251  and a drain electrode  252  are formed to be electrically connected to the source and drain regions  211  and  212  through first contact holes  221  and  241 , and second contact holes  222  and  242 , respectively formed in the gate insulating layer  220  and the interlayer insulating layer  240 , to thereby constitute the second TFT T 2 . 
         [0036]    In addition, concave portions (or trenches)  245  and  225  are formed in the interlayer insulating layer  240  and the gate insulating layer  220 , respectively, in areas surrounding the pixel region  110  (see  FIG. 1 ). Also, the wire lines  253  are formed in the concave portions  245  and  225  thereof. In the aspect shown, the wire lines  253  may be formed to have a lower height than that of a surface of the interlayer insulating layer  240 , such that the interlayer insulating layer  240  protrudes between the wire lines  253 . For example, the wire lines  253  are formed on lower portions of the concave portions  225  and  245 . 
         [0037]    In the aspect shown, the substrate  100  may be made of an insulating material or a metal material. Examples of the insulating material include glass, plastic, and/or other insulators, and examples of the metal material include stainless steel (SUS), and/or other metals. The buffer layer  200  prevents or reduces impurities of the substrate  100  from spreading when the active layer  210  is formed. For example, the buffer layer  200  may include a silicon nitride (SiN) layer or may be formed to have a stacked or layered structure that includes a silicon nitride (SiN) layer and a silicon oxide (SiO 2 ) layer. 
         [0038]    The gate electrode  230  may be made of one or more metals. In an aspect of the present invention, the gate electrode  230  may be an MoW layer, an aluminum layer, a chromium layer, and/or an aluminum/chromium layer. The source and drain electrodes  251  and  252  may be made of metal layers such as a titanium/aluminum layer and/or a titanium/aluminum/titanium layer. The interlayer insulating layer  240  may be made of a material having a Mohs hardness that is larger than that of the wire lines  253 . In various aspects, the interlayer insulating layer  240  may be silicon nitride or silicon oxide. 
         [0039]    A planarization layer  260  is formed on the interlayer insulating layer  240  so as to cover the second TFT T 2  and to fill the concave portions  225  and  245 . A first pixel electrode  310  is formed on the planarization layer  260 and is electrically connected to the drain electrode  252  of the second TFT T 2  through a via hole  261  formed in the planarization layer  260 . Additionally, an organic light emitting layer  330  is formed on the first pixel electrode  310 , and a second pixel electrode  340  is formed on the organic light emitting layer  330 , to thereby constitute the organic light emitting element L 1 . 
         [0040]    The first pixel electrode  310  is electrically separated from an adjacent first pixel electrode (not shown) of an adjacent pixel by a pixel defining layer  320 . T e first pixel electrode  310  contacts the organic light emitting layer  330  through an opening portion  321  provided to the pixel defining layer  320 . In the aspect shown, the first pixel electrode  310  injects holes, and the second pixel electrode  340  injects electrons to the organic light emitting layer  330 , respectively. 
         [0041]    The first pixel electrode  310  may include a first transparent electrode (not shown) made of indium tin oxide (ITO) and/or indium zinc oxide (IZO). The first pixel electrode  310  may further include a conductive reflective layer (not shown) and a second transparent electrode (not shown) on the first transparent electrode depending on a light emitting direction of the organic light emitting element L 1 . The reflective layer increases a light emitting efficiency of the organic light emitting display by reflecting light emitted from the organic light emitting layer  330 . The reflective layer also improves an electrical conductivity of the first pixel electrode  310 , for example. By way of example, the reflective layer may be made of aluminum (Al), an aluminum alloy, silver (Ag), a silver alloy, gold (Au), a gold alloy, and/or other material. The second transparent electrode suppresses oxidation of the reflective layer and improves a work function relationship between the organic light emitting layer  330  and the reflective layer. The second transparent electrode may be made of ITO and/or IZO, similar to the first transparent electrode. 
         [0042]    The organic light emitting layer  330  may further include a light emitting layer to practically or efficiently emit light and an organic layer to effectively transmit carriers such as holes or electrons to the light emitting layer. In various aspects, the organic layer may be disposed on, over, or under the light emitting layer. By way of example, the organic layer may include one or more layers from among a hole injection layer and a hole transmission layer (that are formed between the light emitting layer and the first pixel electrode  310 ) and an electron transmission layer and an electron injection layer (that are formed between the light emitting layer and the second pixel electrode  340 ). 
         [0043]    The second pixel electrode  340  may be made of a transparent conductive layer (not shown) or an opaque conductive layer (not shown) depending on a light emitting direction of the organic light emitting element L 1 . The transparent conductive layer may have a thickness of from 100 to 180 Å. In various aspects, the transparent conductive layer may be made of IZO, ITO, MgAg, or other material. In various aspects, the opaque conductive layer (not shown) may be made of Al, or other material. 
         [0044]    According to this aspect, the concave portions  225  and  245  have the wire lines  253  disposed therein. The concave portions  225  and  245  are respectively formed in the gate insulating layer  220  and the interlayer insulating layer  240 , for example. Accordingly, the interlayer insulating layer  240 , or a portion thereof, protrudes between the wire lines  253 . Also, the interlayer insulating layer  240  has a Mohs hardness that is larger than that of the wire lines  253 . Therefore, even though the planarization layer  260  on the wire lines  253  has the potential to be damaged by an external physical impact because of the wire lines  253  not being sealed by the sealing substrate  400 , the wire lines  253  can be protected from the impact by the protruding interlayer insulating layer  240 , or the protruding portion thereof. As a result, a scratch on the wire lines  253  and a resulting short or an open circuit between the wire lines  253  can be prevented or reduced, and a deterioration in the driving of the pixel can also be prevented or reduced. 
         [0045]    In this aspect, if the concave portions  245  and  225  are formed in the interlayer insulating layer  240  and the gate insulating layer  220 , respectively, is taken as an example, the concave portion  245  may be formed only in the interlayer insulating layer  240  as shown in  FIG. 3 . In the aspect shown, the wire lines  253  are formed to have a lower height than that of the surface of the interlayer insulating layer  240  such that a portion of the interlayer insulating layer  240  protrudes between the wire lines  253 . By way of example, the wire lines  253  are formed on a lower portion of the concave portion  245 . Also, in this aspect, the wire lines  253  are formed on the gate insulating layer  220 , which does not have the concave portion  225 . 
         [0046]    Next, a method of manufacturing an organic light emitting display according to an aspect of the present invention will be described with reference to  FIGS. 4A ,  4 B, and  4 C. Referring to  FIG. 4A , a buffer layer  200  is formed on a pixel substrate  100 . In various aspects, the buffer layer  200  is made of a silicon nitride (SiN) or a stacked structure including a silicon nitride (SiN) layer and a silicon oxide (SiO 2 ) layer. Next, an amorphous silicon layer is deposited on the buffer layer  200 , and a crystallization process and a patterning process are performed thereon, to thereby form an active layer  210  on a pixel region  110  (see  FIG. 1 ). Next, a gate insulating layer  220  is formed on the buffer layer  200  to cover the active layer  210 , a metal layer is deposited on the gate insulating layer  220 , and a patterning process is performed thereon to form a gate electrode  230  on the gate insulating layer  220 . In various aspects, the metal layer on the gate insulating layer  220  includes one selected from a MoW layer, an aluminum layer, a chromium layer, and an aluminum/chromium layer. However, other metals are within the scope of the present invention. 
         [0047]    Next, impurities are doped into both sides of the active layer  210  to form source and drain electrodes  211  and  212 , respectively. Next, an interlayer insulating layer  240  made of silicon nitride (SiN) or silicon oxide (SiO) is formed on the gate insulating layer  220  to cover the gate electrode  230 . Also, the interlayer insulating layer  240  and the gate insulating layer  220  are patterned to form first contact holes  221  and  241 , respectively, to expose the source region  211 , and to form second contact holes  222  and  242 , respectively, to expose the drain region  212 . In the aspect shown, the interlayer insulating layer  240  and the gate insulating layer  220  in the surrounding area of the pixel region  110  are simultaneously patterned to form concave portions  245  and  225  in the interlayer insulating layer  240  and the gate insulating layer  220 , respectively. 
         [0048]    Referring to  FIG. 4B , a metal layer is deposed on or in the interlayer insulating layer  240 , the first contact holes  221  and  241 , the second contact holes  222  and  242 , and the concave portions  225  and  245 , and a patterning process is performed thereon. In various aspects, the metal layer includes a titanium/aluminum layer or a titanium/aluminum/titanium layer. Source and drain electrodes  251  and  252  are then formed to form a second TFT T 2 , and wire lines  253  are formed in the concave portions  225  and  245 . The source and drain electrodes  251  and  252  are electrically connected to the source and drain regions  211  and  212 , respectively. Also, by way of example, the wire lines  253  can be formed at lower portions of the concave portions  225  and/or  245 . 
         [0049]    Referring to  FIG. 4C , a planarization layer  260  is formed on the interlayer insulating layer  240  to cover the second TFT T 2 . The planarization layer  260  fills in the concave portions  225  and  245 . Next, the planarization layer  260  is patterned to form via holes  261  to expose the drain electrode  252  of the second TFT T 2 . Next, a first pixel electrode material layer is deposited on the planarization layer  260  and the via holes  261 , and is patterned by an etching process so that a first pixel electrode  310  is formed that is electrically connected to the drain electrode  252 . 
         [0050]    Next, referring back to  FIG. 2 , a pixel defining layer  320  is formed on the planarization layer  260  to cover the first pixel electrode  310 . Next, a patterning process is performed on the pixel defining layer  320  to form an opening portion  321  to expose the first pixel electrode  310 . Also, an organic light emitting layer  330  is formed on the first pixel electrode  310  of the opening portion  321 . Then, a second pixel electrode  340  is formed thereon, to thereby constitute an organic light emitting element L 1 . 
         [0051]    According to aspects of the present invention, the wire lines  253  are disposed in the concave portions  225  and/or  245  of gate insulating layer  220  and the interlayer insulating layer  240 , respectively. The concave portions  225  and  245  can be simultaneously formed when the first contact holes  221  and  241  and the second contact holes  222  and  242  are formed in the gate insulating layer  220  and the interlayer insulating layer  240 , respectively, so that an additional forming process is not required. 
         [0052]    In various aspects, the gate insulating layer may partially fill the concave portions, in addition to the planarization layer. 
         [0053]    In various aspects, the concave portion or the trench may be any shape, or at any incline. 
         [0054]    In various aspects, the pads  160  of the wires lines  253  may be exposed for electrical contact. In other aspects, portions of the wire lines  253  may be exposed through the planarization layer  260 , and/or other layer, for example. 
         [0055]    Although a few aspects 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 the aspects without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents.