Patent Publication Number: US-2012038844-A1

Title: Method of manufacturing display apparatus and display apparatus

Description:
This application claims priority to Korean Patent Application No. 10-2010-0076974, filed on Aug. 10, 2010, and all the benefits accruing therefrom under 35 U.S.C. §119, the content of which in its entirety is herein incorporated by reference. 
     BACKGROUND OF THE INVENTION 
     (1) Field of the Invention 
     The present invention relates to a method of manufacturing a display apparatus and a display apparatus manufactured using the same. 
     (2) Description of the Related Art 
     A display apparatus, such as a liquid crystal display (“LCD”) and an electrophoretic display apparatus are widely used. 
     The display apparatus includes two substrates facing each other and an image display layer, e.g., a liquid crystal layer or an electrophoretic layer, disposed between the two substrates. The two substrates are coupled to each other and the two substrates are spaced apart from each other by a distance to dispose the image display layer therebetween. 
     A spacer is typically formed on one of the two substrates to maintain the distance between the two substrates, and an adhesive may be used to bond the spacer to the other substrate. A manufacturing process of the display apparatus may be complicated, thereby causing an increase of manufacturing costs and occurrence of defects based on the use of the adhesive. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention obviates the above-mentioned problems by providing a method of manufacturing a display apparatus capable of simplifying a manufacturing process, to thereby reduce manufacturing cost and occurrence of defects. 
     The present invention further provides a display apparatus manufactured using the same. 
     According to an exemplary embodiment of the present invention, a method of manufacturing a display apparatus is provided. The method includes preparing a first substrate and a second substrate, forming a bonding spacer on the first substrate having a first height, and forming a supporting spacer on the second substrate having a second height less than the first height. An image display part is formed on one of the first substrate or the second substrate and the first substrate and the second substrate are coupled together until an upper surface of the supporting spacer contacts with the first substrate, and the second substrate is bonded to the bonding spacer. 
     According to an exemplary embodiment, the bonding spacer is formed by coating a resist on the first substrate, pre-baking the resist at a temperature of about 80° C. to about 100° C. during about 50 seconds to about 70 seconds, exposing the resist to a light, and developing the resist. 
     According to an exemplary embodiment, the bonding spacer may be a barrier. 
     According to an exemplary embodiment, the supporting spacer is formed by coating a resist on the second substrate, pre-baking the resist with a temperature of about 80° C. to about 100° C. during about 50 seconds to about 70 seconds, exposing the resist to a light, developing the resist, and post-baking the resist at a temperature of about 210° C. to about 240° C. during about 15 minutes to about 120 minutes. 
     According to an exemplary embodiment, a sealant may be formed along an end portion of one of the first substrate and the second substrate prior to pressing the first and second substrates. 
     According to an exemplary embodiment, the bonding spacer and the sealant may be post-baked at a temperature of about 100° C. to about 140° C. during about 15 minutes to about 120 minutes after the pressing of the first and second substrates. 
     According to another exemplary embodiment of the present invention, a display apparatus is provided. The display apparatus includes a first substrate, a second substrate facing the first substrate, a bonding spacer arranged on the first substrate. The bonding spacer to divides the first substrate into a plurality of areas, maintains a distance between the first substrate and the second substrate, and bonds the first substrate and the second substrate, and an image display part arranged in the plurality of areas between the first and second substrates. 
     According to an exemplary embodiment, the first substrate includes a first insulating substrate, a gate line formed on the first insulating substrate and extending in a first direction, a first insulating layer formed on the first insulating substrate on which the gate line is formed, a data line formed on the first insulating layer and crossing the gate line, a step-difference compensation pattern arranged on the first insulating layer between the gate line and the data line to compensate for a step-difference between the data line and the first insulating layer, and a switching element connected with the gate line and the data line. 
     According to an exemplary embodiment, the bonding spacer is overlapped with the data line and the step-difference compensation pattern. 
     According to another exemplary embodiment, the bonding spacer is overlapped with the gate line and the step-difference compensation pattern or is overlapped with the data line, the step-difference compensation pattern, and the gate line. 
     According to an exemplary embodiment, the image display part includes an image display layer which absorbs or reflects a light to display an image. The image display layer may be one of a liquid crystal layer, an electrophoretic layer, an electro-wetting layer, or an electrochromic layer. Further, the image display layer may be a cholesteric liquid crystal layer. 
     According to an exemplary embodiment of the present invention, the display apparatus may be manufactured without using an adhesive, and thus, a manufacturing process may be simplified, to thereby reduce manufacturing cost. 
     Further, the distance between the first and second substrates may be stably maintained by the bonding spacer without using an additional adhesive. Therefore, defects occurring in the image display part including the image display layer due to the use of adhesive may be prevented. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other advantages of the present invention will become readily apparent by reference to the following detailed description when considered in conjunction with the accompanying drawings wherein: 
         FIG. 1  is a cross-sectional view illustrating an exemplary embodiment of a display apparatus according to the present invention; 
         FIG. 2  is a flowchart illustrating an exemplary embodiment of a method of manufacturing a display apparatus of  FIG. 1  according to the present invention; 
         FIG. 3  is a cross-sectional view schematically illustrating an exemplary embodiment of a method of manufacturing a display apparatus of  FIG. 1  according to the present invention; 
         FIG. 4  is a cross-sectional view schematically illustrating another exemplary embodiment of a method of manufacturing a display apparatus according to the present invention; 
         FIG. 5  is a cross-sectional view schematically illustrating another exemplary embodiment of a method of manufacturing a display apparatus of  FIG. 4  according to the present invention; 
         FIG. 6  is a cross-sectional view schematically illustrating another exemplary embodiment of a method of manufacturing a display apparatus according to the present invention; 
         FIG. 7  is a cross-sectional view illustrating another exemplary embodiment of a display apparatus according to the present invention; 
         FIG. 8  is a flowchart illustrating another exemplary embodiment of a method of manufacturing a display apparatus according to the present invention; 
         FIG. 9  is a sectional view illustrating an exemplary embodiment of a coupling operation of a first substrate with a second substrate according to the present invention; 
         FIG. 10  is a plan view illustrating another exemplary embodiment of a display apparatus according to the present invention; 
         FIG. 11  is a cross-sectional view taken along line I-I′ of  FIG. 10 ; 
         FIG. 12  is a plan view illustrating an exemplary embodiment of the pixel areas of  FIG. 10  including a bonding spacer according to the present invention; 
         FIG. 13  is a plan view illustrating another exemplary embodiment of a display apparatus according to the present invention; 
         FIG. 14  is a plan view illustrating an exemplary embodiment of the pixel areas PA of  FIG. 13  including a barrier according to the present invention; 
         FIG. 15  is a plan view illustrating another exemplary embodiment of a display apparatus according to the present invention; 
         FIG. 16  is a plan view illustrating another exemplary embodiment of a display apparatus according to the present invention; 
         FIG. 17  is a cross-sectional view illustrating an exemplary embodiment of a display apparatus including an electrophoretic layer as an image display layer according to the present invention; 
         FIG. 18  is a cross-sectional view illustrating an exemplary embodiment of a display apparatus including an electrochromic layer as an image display layer according to the present invention; and 
         FIG. 19  is a cross-sectional view illustrating an exemplary embodiment of a display apparatus including an electro-wetting layer as an image display layer according to the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The invention now will be described more fully hereinafter with reference to the accompanying drawings, in which various embodiments are shown. This invention may, however, be embodied in many different forms, and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of he invention to those skilled in the art. Like reference numerals refer to like elements throughout. 
     It will be understood that when an element is referred to as being “on” another element, it can be directly on the other element or intervening elements may be present therebetween. In contrast, when an element is referred to as being “directly on,” another element, there are no intervening elements present. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. 
     It will be understood that, although the terms “first”, “second”, “third” etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another region, layer or section. Thus, “a first element”, “component”, “region”, “layer” or “section” discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the present invention. 
     The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms, “comprises” and/or “comprising”, or “includes” and/or “including” when used in this specification, specify the presence of stated features, regions, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, regions, integers, steps, operations, elements, components, and/or groups thereof. 
     Spatially relative terms, such as “upper” and the like, may be used herein for ease of description to describe one element or feature&#39;s relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the present disclosure, and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein. 
     Exemplary embodiments of the present invention are described herein with reference to cross section illustrations that are schematic illustrations of idealized embodiments. As such, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and/or tolerances, are to be expected. Thus, embodiments of the present invention should not be construed as limited to the particular shapes of regions illustrated herein but are to include deviations in shapes that result, for example, from manufacturing. For example, a region illustrated or described as flat may, typically, have rough and/or nonlinear features. Moreover, sharp angles that are illustrated may be rounded. Thus, the regions illustrated in the figures are schematic in nature and their shapes are not intended to illustrate the precise shape of a region and are not intended to limit the scope of the present claims. 
     Hereinafter, the present invention will be explained in detail with reference to the accompanying drawings. 
       FIG. 1  is a cross-sectional view illustrating an exemplary embodiment of a display apparatus according to the present invention. 
     Referring to  FIG. 1 , a display apparatus according to an exemplary embodiment includes a first substrate  100 , a second substrate  200 , a bonding spacer ADS, an image display part  300 , and a sealant SL. 
     According to an exemplary embodiment, the first substrate  100  includes a plurality of pixel areas PA and the second substrate  200  is arranged to face the first substrate  100 . 
     According to an exemplary embodiment, the bonding spacer ADS maintains a distance between the first substrate  100  and the second substrate  200  and bonds the first substrate  100  to the second substrate  200 . The bonding spacer ADS may be formed in various shapes. According to one exemplary embodiment, the bonding spacer ADS may be a column spacer. 
     According to an exemplary embodiment, the sealant SL is arranged along an end portion of the first and second substrates  100  and  200  to surround a space between the first and second substrates  100  and  200 . 
     According to an exemplary embodiment, the image display part  300  is arranged in the space surrounded by the first substrate  100 , the second substrate  200 , and the sealant SL to display an image. 
     According to an exemplary embodiment, the image display part  300  includes an image display layer  301  absorbing or reflecting a light to display the image, and at least one electrode (not shown) applying an electric field to the image display layer  301 . Although not shown in  FIG. 1 , the electrode may be formed on either the first substrate  100  or the second substrate  200 . According to an exemplary embodiment, the image display layer  301  is a non-emissive display device, however, it is not particularly limited thereto. According to an exemplary embodiment, the image display layer  301  may be a liquid crystal layer, an electrophoretic layer, an electro-wetting layer, or an electrochromic layer. Further, the image display layer  301  may be a reflective-type image display layer. When the image display layer  301  is the reflective-type image display layer, the light provided from an exterior is visible to a user after being reflected by the image display layer  301 . When the image display layer  301  is a transmissive-type image display layer, the light provided from a backlight included in the display apparatus is visible to a user after being transmitted through the image display layer  301 . According to an exemplary embodiment, the reflective type display apparatus will now be described. 
       FIG. 2  is a flowchart illustrating an exemplary embodiment of a method of manufacturing the display apparatus of  FIG. 1  and  FIG. 3  is a cross-sectional view schematically illustrating an exemplary embodiment of a method of manufacturing the display apparatus of  FIG. 1 . 
     Referring to  FIGS. 1 to 3 , according to an exemplary embodiment, the method includes providing the first substrate  100  and the second substrate  200  separately at operations  11  and  12 . After the first and second substrates are provided, the bonding spacer ADS is formed on the first substrate  100  at operations  21 ,  31  and  41  (described in detail below) and the image display layer  301  is formed on the first substrate  100  at operation  51 . Next, the first substrate  100  and the second substrate  200  are coupled together at operation  60 , and then the first and second substrates  100  and  200  are post-baked at operation  70 . 
     As mentioned above, the first substrate  100  and the second substrate  200  are separately prepared at operations  11  and  12 . 
     Then, according to an exemplary embodiment, bonding spacer ADS are formed on the first substrate  100 . According to an exemplary embodiment, the bonding spacer ADS may be formed on either the first substrate  100  or the second substrate  200 , or on both of the first and second substrates  100  and  200  such that the bonding spacer ADS formed on the first substrate  100  are not overlapped with the bonding spacer ADS formed on the second substrate  200  while coupling the first and second substrates  100  and  200  together. According to an exemplary embodiment, formation of the bonding spacer ADS formed on the first substrate  100  will now be described with reference to operations  21 ,  31  and  41  shown in  FIG. 2 . However, operations  21 ,  31  and  41  may also be performed to form the bonding spacer ADS on the second substrate  200 . 
     At operation  21 , the bonding spacer ADS is formed using a resist. According to an exemplary embodiment, the resist is a photosensitive organic polymer material, but the material should not be limited thereto. The resist may be various photosensitive polymers in which a photopolymerization reaction or a photodegradation reaction may occur. 
     The resist is then patterned through a photolithography process. As shown in  FIGS. 1 to 3 , according to an exemplary embodiment, each bonding spacer ADS has a trapezoidal shape, however, the shape of the bonding spacer ADS should not be limited thereto. That is, the bonding spacer ADS may be formed in other shapes (e.g., a rectangular shape) according to a condition of the photolithography process. 
     Hereinafter, the photolithography process will now be described. The resist in liquid form is coated on the first substrate  100  at operation  21 . According to an exemplary embodiment, the resist may be coated using a spin coating method. The resist may have a thickness of about 2 micrometers to about 4 micrometers. The resist is pre-baked at a temperature of about 80° C. to about 100° C. during about 50 seconds to about 70 seconds at operation  31 . According to an exemplary embodiment, the solvent inside the resist is partially volatilized during the pre-bake process, and thus, the resist is flexible and its viscosity is higher. However, the resist is not fully baked during this operation. Then, at operation  41 , the pre-baked resist is exposed to a light (e.g., an ultraviolet ray) using a mask which has a pattern corresponding to the bonding spacer ADS and the resist is developed. As a result of the developing operation, the resist is patterned. The patterned resist may have a width of about 10 micrometers to about 30 micrometers. 
     A sealant SL is then formed on the first substrate  100 . The sealant SL is formed along the end portion of the first substrate  100  to provide the space in which the image display layer  301  is formed. 
     Then, at operation  51 , the image display layer  301  is formed on the first substrate  100  on which the sealant SL is formed. When the image display layer  301  is a fluid having a viscosity, the image display layer  301  may be formed through a one-drop filling (“ODF”) process or an inkjet process, which drips the fluid on the substrate. 
     Next at operation  60 , the first substrate  100  on which the bonding spacer ADS is formed is arranged to face the second substrate  200 , and at least one of the first substrate  100  or the second substrate  200  is coupled together e.g., by pressing. The bonding spacer ADS is bonded to the second substrate  200  as a result of the coupling. 
     The first substrate  100  and the second substrate  200  are then post-baked at a temperature of about 100° C. to about 140° C. during about 15 minutes to about 120 minutes (S 70 ). The post-bake operation is performed to simultaneously bake the sealant SL and the bonding spacer ADS. When the post-bake operation is completed, the sealant SL and the bonding spacer ADS are fully baked. Since the bonding spacer ADS is fully baked while being bonded to the second substrate  200 , the distance between the first and second substrates  100  and  200  may be stably maintained. 
     When a display apparatus is manufactured according to the above-described method, the distance between the first and second substrates  100  and  200  may be stably maintained as mentioned above, and in addition, the first and second substrates  100  and  200  may be bonded to each other without using additional adhesive. Therefore, defects in association with the use of an adhesive, for example, when an adhesive is mixed with the image display layer  301 , may be reduced. 
       FIG. 4  is a cross-sectional view schematically illustrating another exemplary embodiment of a method of manufacturing a display apparatus according to the present invention. 
     The same reference numerals denote the same elements as in the exemplary embodiment shown in  FIG. 3 , and thus the detailed descriptions of the same elements will be omitted. 
     Referring to  FIG. 4 , an exemplary embodiment of a display apparatus according to the is provided with an inorganic layer IOL disposed between a bonding spacer ADS and a second substrate  200 . Since the second substrate  200  includes a material, such as glass, quartz or silicon, the inorganic layer IOL is disposed between the second substrate  200  and the bonding spacer ADS to improve an adhesive property between the second substrate  200  and the bonding spacer ADS which includes an organic polymer. According to an exemplary embodiment, the inorganic layer IOL may include silicon nitride (SiNx). 
     The display apparatus according to this exemplary embodiment of the present invention is manufactured as follows. When first substrate  100  and the second substrate  200  are separately prepared at operations  11  and  12  shown in  FIG. 2 , the bonding spacer ADS and the sealant SL are formed on the first substrate  100  at operations  21 ,  31  and  41 . Then, at operation  51 , the image display layer  301  is formed on the first substrate  100  and the first substrate  100  and the second substrate  200  are coupled together. After that, the first and second substrates  100  and  200  are baked at operation  70 . 
     However, in this exemplary embodiment, the inorganic layer IOL is formed on the second substrate  200  before the first and second substrates  100  and  200  are coupled together as shown in  FIG. 4 . The inorganic layer IOL is formed to correspond to the bonding spacer ADS such that the inorganic layer IOL may make contact with an upper surface of the bonding spacer ADS when the first and second substrates  100  and  200  are coupled together. According to an exemplary embodiment, the inorganic layer IOL may be formed by depositing an inorganic material such as silicon nitride on an insulating substrate and patterning the inorganic material through a photolithography process. 
     According to exemplary embodiments, the display apparatus may be manufactured using other methods. 
       FIG. 5  is a cross-sectional view schematically illustrating another exemplary embodiment of a method of manufacturing the display apparatus of  FIG. 4  according to the present invention. 
     As shown in  FIG. 5 , a first substrate  100  and a second substrate  200  are separately prepared and the bonding spacer ADS is formed on the first substrate  100 . 
     Further, according to an exemplary embodiment, the inorganic layer IOL is formed on the second substrate  200 . The inorganic layer IOL is formed to corresponding to the bonding spacers ADS when the first and second substrates  100  and  200  coupled together. An inorganic alignment layer IOAN may be formed on the second substrate  200  to cover the inorganic layer IOL. The inorganic alignment layer IOAN may include the inorganic material such as silicon nitride (SiNx) or silicon oxide (SiOx). The sealant SL is formed along the end portion of the second substrate  200 . Then, the image display layer  301  is formed on the second substrate  200  on which the inorganic layer IOL, the inorganic alignment layer IOAN, and the sealant SL are formed. The first substrate  100  and the second substrate  200  are coupled together, and then the first and second substrates  100  and  200  are post-baked as described above to manufacture the display apparatus. 
     Since the image display layer  301  includes a liquid crystal layer, the inorganic alignment layer IOAN may align liquid crystal molecules of the liquid crystal layer and hold the liquid crystal molecules without spreading out the liquid crystal molecules. That is, the inorganic alignment layer IOAN is formed to change a surface energy of the second substrate  200 , and thus a surface tension between the inorganic alignment layer IOAN and the liquid crystal layer increases to weaken spreadability of the image display layer  301 . Therefore, according to an exemplary embodiment, the image display layer  301  may be arranged according to a pattern of the inorganic layer IOL. When the inorganic alignment layer IOAN is not formed, the liquid crystal layer may be formed to directly contact either a first electrode or a second electrode which will be described later. When the liquid crystal layer directly contacts the first electrode or the second electrode, the spreadability of the liquid crystal layer becomes higher than when the inorganic alignment layer IOAN exists. Thus, the liquid crystal layer may be formed using the inkjet method such that the liquid crystal layer may be formed in a predetermined area. 
       FIG. 6  is a cross-sectional view schematically illustrating another exemplary embodiment of a method of manufacturing a display apparatus according to the present invention. 
     Referring to  FIG. 6 , a display apparatus according to the an exemplary embodiment includes a second substrate  200  on which bonding spacer ADS, a sealant SL, and an image display layer  301  are formed. As mentioned above, a first substrate  100  and the second substrate  200  are separately prepared. Then, the bonding spacer ADS and the sealant SL are formed on the second substrate  200  and the image display layer  301  is formed on the second substrate  200 . The first and second substrates  100  and  200  are coupled together, and the first and second substrates  100  and  200  are post-baked. 
       FIG. 7  is a cross-sectional view illustrating another exemplary embodiment of a display apparatus according to the present invention. 
     Referring to  FIG. 7 , a display apparatus according to an exemplary embodiment includes a first substrate  100 , a second substrate  200 , a bonding spacer ADS, a supporting spacer SS, an image display part  300 , and a sealant SL. 
     According to an exemplary embodiment, the supporting spacer SS maintains a distance between the first and second substrates  100  and  200 . Although the first substrate  100  and the second substrate  200  are coupled together before the bonding spacer ADS are not fully baked, the distance between the first and second substrates  100  and  200  may be uniformly maintained over the entire area of the first and second substrates  100  and  200  due to the use of the supporting spacer SS. The supporting spacer SS has a uniform height regardless of pressure applied when the supporting spacer SS is completely baked. 
       FIG. 8  is a flowchart illustrating an exemplary embodiment of a method of manufacturing a display apparatus according to the present invention.  FIG. 9  is a sectional view illustrating an exemplary embodiment of a coupling operation the first substrate with the second substrate as shown in  FIG. 7 , according to the present invention. 
     Referring to  FIG. 8 , the method includes preparing the first substrate  100  and the second substrate  200  are separately at operations  11  and  12 , and forming the bonding spacers ADS on either the first substrate  100  or the second substrate  200  (at operations  21 ,  31 , and  41 ). The supporting spacer SS is formed on the first or second substrate  100  or  200  on which the bonding spacer ADS is not formed. According to this exemplary embodiment, the supporting spacer SS is formed on the second substrate  200  at operations  22 ,  32 ,  42 , and  52  which are similar to operations  21 ,  31 ,  41  except a post-bake operation is performed at operation  52  (to be described later), and the image display layer  301  is formed on the first substrate  100  at operation  51 . The first and second substrates  100  and  200  are coupled together, and the first and second substrates  100  and  200  are post-baked at operation  70 . 
     Thus, as mentioned above, the first substrate  100  and the second substrate  200  are separately prepared at operations  11  and operation  12 . Then, the bonding spacer ADS is formed on either the first substrate  100  or the second substrate  200  at operations  21 ,  31 , and  41 , and the supporting spacer SS is formed on the first or second substrate  100  or  200  on which the bonding spacer ADS is not formed. In this exemplary embodiment, the supporting spacer SS is formed on the second substrate  200  at operations  22 ,  32 ,  42 , and  52 . For explanation purposes, in this exemplary embodiment, a structure that the bonding spacer ADS is formed on the first substrate  100  and the supporting spacer SS is formed on the second substrate  200  will be described however, exemplary embodiments are not limited thereto. 
     The bonding spacer ADS is formed similar to the method described in  FIG. 2 . 
     Further, the supporting spacer SS may be formed using a resist similar to the bonding spacer ADS. According to an exemplary embodiment, the supporting spacer SS is formed to have a height less than that of the bonding spacer ADS. That is, the bonding spacer ADS has a first height H 1  and the supporting spacer SS has a second height H 2  such that the first height H 1  is greater than the second height H 2 . The resist may be a photosensitive organic material and patterned through a photolithography process. Details regarding the photolithography process will now be described. 
     At operation  22 , the resist in liquid form is coated on the first substrate  100 . According to an exemplary embodiment, the resist may be coated using a spin coating method. 
     At operation  32 , the resist is pre-baked at a temperature of about 80° C. to about 100° C. during about 50 seconds to about 70 seconds. The solvent inside the resist may be partially volatilized during the pre-bake operation, and thus, the resist is flexible and its viscosity is high. However, the resist is not fully baked through the pre-bake operation. 
     Then, at operation  42 , the baked resist is exposed to the ultraviolet ray using a mask which has a pattern corresponding to the supporting spacer SS and the mask is formed in an area where the bonding spacer ADS is not formed such that the mask is not overlapped with the bonding spacer ADS when the first and second substrates  100  and  200  are coupled together. When the exposed resist is developed, the resist is patterned. 
     At operation  52 , the patterned resist is post-baked at a temperature of about 210° C. to about 240° C. during about 15 minutes to about 120 minutes. After the post-bake process, the resist becomes the supporting spacer SS which is fully baked. Since the supporting spacer SS is fully baked through the post-bake operation, the supporting spacer SS has a relatively lower viscosity and elasticity than that of the bonding spacer ADS. 
     Although not shown in  FIG. 8 , according to an exemplary embodiment, the sealant SL may be formed on either the first substrate  100  or the second substrate  200 . The sealant SL is formed along an end portion of the first substrate  100  or the second substrate  200  to provide a space in which the image display layer  301  is formed. In this exemplary embodiment, the sealant SL may be formed on the first substrate  100  however exemplary embodiments are not limited hereto. 
     Then, at operation  51 , the image display layer  301  is formed on the first substrate  100  on which the sealant SL is formed. When the image display layer  301  is a fluid having a viscosity, the image display layer  301  may be formed through a one-drop filling (“ODF”) process or an inkjet process that drips the fluid on the substrate. 
     The first substrate  100  is placed to face the second substrate  200 , and a pressure P is applied to at least one of the first substrate  100  or the second substrate  200  to couple the first substrate  100  to the second substrate  200 . The first and second substrates  100  and  200  are pressed together until the distance between the first and second substrates  100  and  200  is equal to the second height H 2 . 
     Since the bonding spacer ADS is more flexible, the bonding spacer ADS may be pressed until the first height H 1  of the bonding spacer ADS becomes equal to the second height H 2 . When the bonding spacer ADS is pressed, a contact area between the bonding spacer ADS and the second substrates  200  increases, and an adhesive property of the bonding spacer ADS may be improved by the pressure P. Thus, the bonding spacer ADS may be stably bonded to the second substrate  200 . The supporting spacer SS has no flexibility after performing the post-bake process, thereby maintaining the second height H 2  regardless of the pressure P. As a result, the distance between the first and second substrates  100  and  200  may be uniformly maintained over the entire area by the supporting spacer SS. 
     At operation  70 , the first and second substrates  100  and  200  are post-baked at a temperature of about 100° to about 140° during about 15 minutes to about 120 minutes. The post-bake operation is performed to fully bake the sealant SL and the bonding spacer ADS. 
     According to the above-described method, the distance between the first and second substrates  100  and  200  may be stably maintained and the first and second substrates  100  and  200  may be bonded to each other without using an additional adhesive. 
     Further, according to an exemplary embodiment, the bonding spacer ADS may be used as a barrier to divide the image display layer  301  into a plurality of areas. Thus, no additional barrier is required to divide the image display layer  301 , to thereby simplifying the manufacturing method. 
       FIG. 10  is a plan view illustrating another exemplary embodiment of a display apparatus according to the present invention, and  FIG. 11  is a cross-sectional view taken along line I-I′ of  FIG. 10 . 
     The display apparatus according to this exemplary embodiment is manufactured using the same method as shown in  FIG. 2  and the bonding spacer ADS is used as a barrier instead of a column spacer. In addition, the display apparatus according to this exemplary embodiment includes a liquid crystal layer as the image display layer  301 . The supporting spacer SS is omitted in this exemplary embodiment, however it should not be limited thereto. Thus, if the supporting spacer SS is included it may be formed using the same method as shown in  FIG. 8 . 
     Referring to  FIGS. 10 and 11 , according to an exemplary embodiment, the display apparatus includes a first substrate  100 , a second substrate  200 , a bonding spacer ADS, an image display part  300 , and a sealant (not shown). 
     The display apparatus includes a plurality of pixel areas PA displaying an image and a non-pixel area formed along with an end portion of the display apparatus to surround the pixel areas. The sealant is arranged in the non-pixel area along with the end portions of the first substrate  100  or the second substrate  200  as shown in  FIGS. 1 to 9 . 
     In  FIGS. 10 and 11 , an exemplary embodiment of a pixel area PA is described for explanation purposes, however, the pixel areas PA are arranged in a matrix configuration having a plurality of rows and columns. Each pixel areas PA have the same structure and function, therefore one pixel area PA will be described in detail. In addition, according to an exemplary embodiment, each pixel area PA has a rectangular shape as shown in  FIG. 10 , but the shape of the pixel area PA should not be limited to the rectangular shape. That is, the pixel area PA may have various shapes, such as a V-shape or Z-shape. 
     According to an exemplary embodiment, the first substrate  100  includes a first insulating substrate  110 , a first insulating layer  113 , a gate line GL, a data line DL, a step-difference compensation pattern SCP, a switching element e.g., a thin film transistor (“TFT”), and a second insulating layer  115 . 
     The gate line GL is arranged on the first insulating substrate  110  and extended in a first direction D 1 . 
     The first insulating layer  113  is formed on the first insulating substrate  110  on which the gate line GL is formed. 
     The data line DL is arranged on the first insulating layer  113  and cross the gate line GL. The data line DL includes a first data line portion DL 1  extended in a second direction D 2  that is substantially perpendicular to the first direction D 1  and a second data line portion DL 2  connected to the first data line portion DL 1  and protruded to the first direction D 1 . The second data line portion DL 2  is arranged adjacent to the gate line GL. 
     According to an exemplary embodiment, the step-difference compensation pattern SCP is arranged on the first insulating layer  113  between the gate line GL and the data line DL. The step-difference compensation pattern SCP is used to compensate for a step difference between the data line DL and the first insulating layer  113 , and an upper surface of the step-difference compensation pattern SCP is arranged on a same plane as an upper surface of the data line DL. As shown in the plan view, the step-difference compensation pattern SCP is arranged in the second direction D 2  in which the first data line portion DL 1  is extended. Thus, the step-difference compensation pattern SCP is positioned at both sides of the gate line GL near an area where the data line DL crosses the gate line GL. The step-difference compensation pattern SCP may include an inorganic material. The inorganic material may be silicon nitride (SiNx), amorphous silicon (a-Si), or impurity-doped amorphous silicon (n+a-Si). 
     According to an exemplary embodiment, a thin film transistor TFT is arranged adjacent to the area where the data line DL crosses the gate line GL and includes a gate electrode GE, a semiconductor layer SM, a source electrode SE, and a drain electrode DE. 
     According to an exemplary embodiment, the gate electrode GE is branched from the gate line GL. The semiconductor layer SM is formed on the first insulating layer  113  to overlap with the gate electrode GE. The source electrode SE is branched from the data line DL and is overlapped with a portion of the semiconductor layer SM. The drain electrode DE is spaced apart from the source electrode SE and overlapped with a portion of the semiconductor layer SM. The semiconductor pattern SM forms a conductive channel between the source electrode SE and the drain electrode DE. 
     According to an exemplary embodiment, the second insulating layer  115  is arranged on the first insulating layer  113  on which the source and drain electrodes SE and DE are formed. The second insulating layer  115  is provided with a contact hole CH formed therethrough to partially expose the drain electrode DE, and a first electrode EL 1 , which will be described later, is connected to the drain electrode DE through the contact hole CH. 
     According to an exemplary embodiment, the step-difference compensation pattern SCP may be formed through a separate patterning process, or according to another exemplary embodiment, the step-difference compensation pattern SCP may be formed from the same layer as the semiconductor pattern SM. Thus, the semiconductor pattern SM and the step-difference compensation pattern SCP may be substantially simultaneously patterned, to thereby form the step-difference compensation pattern SCP without an additional process. 
     As further shown in  FIG. 11 , the second substrate  200  is arranged to face the first substrate  100 . The second substrate  200  includes a second insulating substrate  210 . 
     According to an exemplary embodiment, the bonding spacer ADS is arranged on the first substrate  100 . The bonding spacer ADS maintains a distance between the first and second substrates  100  and  200  and bonds the first substrate  100  to the second substrate  200 . In this exemplary embodiment, the bonding spacer ADS may be used as a barrier to divide the first substrate  100  into a plurality of areas. Since the barrier is formed between the first and second substrates  100  and  200 , the barrier may divide a space between the first and second substrates  100  and  200  into a plurality of areas. 
     According to an exemplary embodiment, the plurality of areas divided by the bonding spacer ADS may have various shapes. Further, the bonding spacer ADS may be formed along an end portion of the pixel area PA. The bonding spacer ADS is formed in a straight line shape along the second direction D 2  in which the first data line portion DL 1  is extended and the bonding spacer ADS is overlapped with the first data line DL 1  and the step-difference compensation pattern SCP. According to an exemplary embodiment, the bonding spacer ADS has a width greater than that of the first data line portion DL 1 . The bonding spacer ADS contacts other elements and the contact size between the bonding spacer ADS and the elements may change based on a pixel design and a process margin. Further, the bonding spacer ADS may be overlapped with a portion of the second data line portion DL 2 . 
     The image display part  300  is disposed between the first substrate  100  and the second substrate  200  in a space defined by the first substrate  100 , the second substrate  200 , and the bonding spacer ADS. 
     The image display part  300  includes a first electrode EL 1 , a second electrode EL 2 , and an image display layer  301  to absorb or reflect an external light, thereby displaying an image. 
     Referring to  FIGS. 10 and 11 , the first electrode EL 1  is arranged on the first substrate  100  in one-to-one correspondence relationship with the pixel area PA. The first electrode EL 1  is arranged on the second insulating layer  115 . The first electrode EL 1  includes a metal reflective material to reflect the light. The first electrode EL 1  is electrically connected to the drain electrode DE through the contact hole CH formed through the second insulating layer  115 . 
     The second electrode EL 2  is formed on the second insulating substrate  210 . The second electrode EL 2  receives a common voltage, and the second electrode EL 2  and the first electrode EL 1  generates an electric field therebetween. The second electrode EL 2  is formed on the second insulating substrate  210  using a transparent material. 
     According to an exemplary embodiment, the image display layer  301  is a liquid crystal layer  310 . The liquid crystal layer  310  is controlled by the electric field to display the image. The liquid crystal layer  310  may be a cholesteric liquid crystal layer, and thus the display apparatus may be a reflective-type display apparatus. The cholesteric liquid crystal layer includes a periodical spiral structure with a constant pitch and selectively reflects the light according to the constant pitch. Therefore, the cholesteric liquid crystal layer may reflect a red light, a green light and a blue light according to its pitch. Thus, liquid crystal layers each reflecting the red light, the green light, and the blue light are respectively disposed in the areas of the image display layer  301 , which are divided by the bonding spacer ADS. 
     According to an exemplary embodiment, when the display apparatus is the reflective-type display apparatus, the bonding spacer ADS may be formed to have a white color which has a high reflectivity with respect to the external light. In the reflective-type display apparatus, the bonding spacer ADS may cover the data line without forming an additional black matrix. In addition, since the bonding spacer ADS has the white color, brightness of the reflective-type display apparatus may increase. 
       FIG. 12  is a plan view illustrating an exemplary embodiment of the pixel areas including the bonding spacer of  FIG. 10 . 
     Referring to  FIG. 12 , the first substrate  100  includes the pixel areas PA. The bonding spacers ADS are at the end portion of each pixel area PA. The bonding spacers ADS are extended in the second direction D 2  and arranged in the first direction D 1 . The areas divided by the bonding spacers ADS are filled with a red-reflective cholesteric liquid crystal layer, a green-reflective cholesteric liquid crystal layer, and a blue-reflective cholesteric liquid crystal layer. As shown in  FIG. 12 , the bonding spacers ADS are disposed between the pixel areas PA representing different colors and not disposed between the pixel areas PA representing same colors. Thus, the pixel areas PA representing the same colors may be filled with the cholesteric liquid crystal layer having the color corresponding to the pixel areas PA representing the same colors simultaneously. 
     According to an exemplary embodiment, in the display apparatus, when an alignment direction of liquid crystal molecules is changed by the electric field, an amount of light transmitting through the liquid crystal layer is controlled, thereby displaying the image. Since the cholesteric liquid crystal layer displays colors, no separate color filter is required even when displaying color images. 
     According to an exemplary embodiment, the second data line portion DL 2  is protruded to the first direction D 1  in order to minimize the step difference on the surface of the first substrate  100  corresponding to the area where the bonding spacer ADS is formed. Thus, the bonding spacer ADS is not overlapped with an area where the data line DL crosses the gate line GL. Also, since the second data line portion DL 2  is protruded to the first direction D 1 , the step difference generated between the first insulating layer  113  and the first and second data line portions DL 1  and DL 2  may be compensated by the step-difference compensation pattern SCP. Therefore, the first substrate  100  includes a flat surface in an area in which the bonding spacer ADS is formed, so that the leakage of the liquid crystal to the adjacent pixel areas PA may be prevented. 
       FIG. 13  is a plan view illustrating an exemplary embodiment of a display apparatus according to the present invention, and  FIG. 14  is a plan view illustrating the pixel areas PA including a barrier as shown in  FIG. 13 . In  FIGS. 13 and 14 , the same reference numerals denote the same elements in  FIGS. 10 and 11 , and thus detailed descriptions of the same elements will be omitted. 
     Referring to  FIGS. 13 and 14 , a bonding spacer ADS is formed to surround each pixel area PA unlike the bonding spacer ADS shown in  FIG. 12 . That is, the bonding spacer ADS is overlapped with the data line DL and the step-difference compensation pattern SCP in the second direction D 2  and overlapped with the gate line GL in the first direction D 1 . Therefore, a space defined by a first substrate  100 , a second substrate  200 , and the bonding spacer ADS is formed corresponding to each of the pixel areas PA. 
     According to an exemplary embodiment, the bonding spacer ADS may be formed to have a white color having a high reflectivity with respect to the external light. Although an additional black matrix is not formed, the display apparatus may cover the gate line GL and the data line DL using the bonding spacer ADS. Also, when the bonding spacer ADS has the white color, an amount of light reflected by the bonding spacer ADS increases, thereby improving the brightness of the display apparatus. 
     According to this exemplary embodiment, a cholesteric liquid crystal layer may be arranged in each pixel area PA to display a different color from an adjacent pixel area PA. In one exemplary embodiment, when a red-reflective cholesteric liquid crystal layer is arranged in a pixel area PA, a green-reflective cholesteric liquid crystal layer or a blue-reflective cholesteric liquid crystal layer is arranged in the pixel areas PA adjacent to the one pixel area PA in which the red-reflective cholesteric liquid crystal layer is arranged. 
       FIG. 15  is a plan view illustrating another exemplary embodiment of a display apparatus according to the present invention. In  FIG. 15 , the same reference numerals denote the same elements in  FIGS. 10 and 11 , and thus detailed descriptions of the same elements will be omitted. 
     Referring to  FIG. 15 , a bonding spacer ADS may have a similar structure as the bonding spacer ADS shown in  FIG. 12 , however, the bonding spacer ADS according to this exemplary embodiment includes a width less than that of the first data line portion DL 1 . In addition, the bonding spacer ADS includes a width greater than that of an area where the bonding spacer ADS is overlapped with the first data line portion DL 1  to fully cover the step-difference compensation pattern SCP. 
     Therefore, according to an exemplary embodiment, the bonding spacer ADS covers a crevice that may be produced between the step-difference compensation pattern SCP and the data line DL. As a result, a first substrate  100  may be formed to have a flat surface corresponding to the area where the bonding spacer ADS is formed, thereby reducing leakage of the liquid crystal molecules to the adjacent pixel area PA. 
       FIG. 16  is a plan view illustrating another exemplary embodiment of a display apparatus according to the present invention. In  FIG. 16 , the same reference numerals denote the same elements in  FIGS. 10 and 11 , and thus detailed descriptions of the same elements will be omitted. 
     Referring to  FIG. 16 , according to an exemplary embodiment, a bonding spacer ADS shown may have a similar structure as the bonding spacer ADS shown in  FIG. 12 , however the bonding spacer ADS includes a double-wall shape. That is, the bonding spacer ADS includes a first bonding spacer ADS 1  and a second bonding spacer ADS 2  that are spaced apart from each other by the first data line DL 1  while being adjacent to each other. The first bonding spacer ADS 1  and the second bonding spacer ADS 2  are extended in a second direction D 2 . The first and second bonding spacers ADS 1  and ADS 2  may be partially overlapped with the first data line portion DL 1 . In  FIG. 16 , according to an exemplary embodiment, the first and second bonding spacers ADS 1  and ADS 2  are not overlapped with the first data line DL 1 . 
     According to an exemplary embodiment, one of the first and second bonding spacers ADS 1  and ADS 2  prevents leakage of the liquid crystal molecules to adjacent pixel areas PA, the other bonding spacer ADS 1  or ADS 2  prevents the leakage of the liquid crystal molecules. As a result, the leakage of the liquid crystal molecules may be prevented. 
     As described above, according to an exemplary embodiment the image display layer  301  is a liquid crystal layer  310  according to an exemplary embodiment, however it is not limited hereto According to another exemplary embodiment, the image display layer  301  may be an electrophoretic layer  320  as described below. 
       FIG. 17  is a cross-sectional view illustrating an exemplary embodiment of a display apparatus including the electrophoretic layer as the image display layer according to the present invention.  FIG. 17  is a cross-sectional view corresponding to a line II-IF of  FIG. 13 . In  FIG. 17 , the same reference numerals denote the same elements in  FIG. 11 , and thus the detailed descriptions of the same elements will be omitted. 
     Referring to  FIGS. 13 to 17 , in this exemplary embodiment, the image display layer  301  is the electrophoretic layer  320 . 
     According to an exemplary embodiment, the electrophoretic layer  320  includes an insulating medium  323  and charged particles  325  and  327 . The insulating medium  323  corresponds to a dispersive medium in a dispersion system where the charged particles  325  and  327  are dispersed. The charged particles  325  and  327  include white charged particles  325  and non-white charged particles  327 . The non-white charged particles  327  may have a black color. The white charged particles  325  and the non-white charged particles  327  are charged to have mutually opposite polarities. 
     According to an exemplary embodiment, the second substrate  200  includes a color filter layer CF to display colors. The color filter layer CF is disposed between the second insulating substrate  210  and the second electrode EL 2 . The color filter layer CF displays a red color R, a green color G, and a blue color B corresponding to each pixel area PA. 
     According to an exemplary embodiment, when the thin film transistor TFT is turned on in response to a driving signal applied through the gate line GL, an image signal provided through the data line DL is transmitted to the first electrode EL 1  through the turned-on thin film transistor TFT. Thus, an electric field is generated between the first electrode EL 1  and the second electrode EL 2  to which the common voltage is applied. The charged particles  325  and  327  move according to the electric field, and thus, an external light incident to the electrophoretic layer  320  is absorbed or reflected by the charged particles  325  and  327  to display an image. 
     Although not shown in figures, according to another exemplary embodiment, the electrophoretic layer  320  may include a plurality of capsules. When the electrophoretic layer  320  includes the capsules, the charged particles  325  and  327  and the insulating medium  323  are provided in the capsules. According to another exemplary embodiment, when the charged particles have colors, the color filter layer CF may be omitted. Also, according to another exemplary embodiment, the electrophoretic layer  320  may include an electrophoretic emulsion. The electrophoretic emulsion includes a non-polar solvent which forms a continuous phase and a polar solvent that is dispersed by the non-polar solvent and forms a droplet controlled by the electric field generated by the first and second electrodes EL 1  and EL 2 . The polar solvent includes dyes which are insoluble in the non-polar solvent and soluble in the polar solvent, so that the polar solvent may display a black color or a white color by the dyes. Therefore, the polar solvent may have a better mobility or cohesive force than the non-polar solvent by the electric field. 
     According to another exemplary embodiment, the image display layer  301  may be an electrochromic layer  330 . 
       FIG. 18  is a cross-sectional view illustrating an exemplary embodiment of a display apparatus including the electrochromic layer  330  as the image display layer according to the present invention. In  FIG. 18 , the same reference numerals denote the same elements in  FIG. 17 , and thus the detailed descriptions of the same elements will be omitted. 
     The electrochromic layer  330  has shown different extents of oxidation reaction and reduction reaction, and a transparency of the electrochromic layer  330  is controlled by the oxidation and reduction difference. The electrochromic layer  330  displays an image by the voltage applied to the first and second electrodes EL 1  and EL 2 . 
     According to an exemplary embodiment, the electrochromic layer  330  is formed with at least one inorganic compound selected from the group consisting of tungsten oxide (WO 3 ), molybdenum oxide (MoO 3 ) and iridium oxide (IrOx) or at least one organic compound selected from the group consisting of viologen, rare-earth phthalocyanine, and styryl. Also, the electrochromic layer  330  may be formed with at least one conductive polymer selected from the group including polypyrrole, polythiophene, and polyaniline. 
     According to another exemplary embodiment, the image display layer  301  may be an electro-wetting layer  340 . 
       FIG. 19  is a cross-sectional view illustrating an exemplary embodiment of a display apparatus including the electro-wetting layer  340  as the image display layer  301  according to the present invention. In  FIG. 19 , the same reference numerals denote the same elements in  FIG. 18 , and thus the detailed descriptions of the same elements will be omitted. Referring to  FIG. 19 , the image display part  300  includes the first electrode EL 1  and the electro-wetting layer  340 , and the second electrode EL 2  is omitted. 
     In the electro-wetting layer  340 , an electrocapillary phenomenon occurs, in which an interfacial surface tension is changed by electric charges existing on an interface of an electrically conductive fluid to vary a contact angle. The electro-wetting is a technique which uses the electrocapillary phenomenon to vary the contact angle of the electrically conductive fluid and interfaces of the two fluids by applying the voltage to the electrically conductive fluid when the conductive fluid makes contact to a non-conductive fluid on the first electrode and controlling the surface tension of the electrically conductive fluid. 
     According to an exemplary embodiment, the electro-wetting layer  340  includes a first fluid  345  and a second fluid  343  that are not mixed with each other. The first fluid  345  may be a black fluid. The electro-wetting layer  340  changes the distribution of the first and second fluids  343  and  345  according to the electric field, to thereby block or transmit the external light. 
     According to an exemplary embodiment, the first fluid  345  and the second fluid  343  may have different electric conductivity. In one exemplary embodiment, the first fluid  345  may have the electric conductivity and the second fluid  343  may have electric insulating property. In an exemplary embodiment, the first fluid  345  is an electrolyte of which solvent is water and the second fluid  343  is oil. 
     According to an exemplary embodiment, when the voltage is applied to the first electrode EL 1 , the surface tension of the first fluid  345  is weakened and covers the entire surface of each pixel area PA, thereby displaying the black color. According to another exemplary embodiment, when the voltage is not applied to the first electrode EL 1 , the surface tension of the first fluid  345  becomes stronger and the first fluid  345  congregates in a certain area of each pixel area PA, to thereby transmit the light. 
     Although exemplary embodiments have been described, it is understood that the present invention should not be limited to these exemplary embodiments but various changes and modifications can be made by one ordinary skilled in the art within the spirit and scope of the present invention as hereinafter claimed. 
     For example, various exemplary embodiments of the image display layer have been described, however the image display layer should not be limited thereto. That is, an electro-fluidic layer or other types of layer may also be used as the image display layer. In addition, the exemplary embodiments of the present invention have been mainly described with reference to the reflective-type display apparatus, but the display apparatus should not be limited thereto. That is, the above-described exemplary embodiments may be applied to a transmissive-type display apparatus employing a separate light source.