Patent Publication Number: US-2009219478-A1

Title: Display device and method of manufacturing the display device

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority from and the benefit of Korean Patent Application No. 10-2008-0018199, filed on Feb. 28, 2008, which is hereby incorporated by reference for all purposes as if fully set forth herein. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present disclosure relates to a display device. 
     2. Discussion of the Background 
     There are many different types of display devices. Particularly, liquid crystal displays (LCDs), which may be thin and lightweight and have improved performance due to developments in semiconductor technology, have been widely used as the display devices. 
     Light transmittance of the LCDs is determined by an alignment state of liquid crystal molecules. Since the light transmittance is controlled by physical movement of the liquid crystal molecules, the response speed of an LCD may be low. 
     Recently, a blue-phase liquid crystal having a relatively fast response speed of about 3 μm/s has been developed. The blue-phase liquid crystal may have a very narrow operational temperature range. Therefore, a monomer may be added to the blue-phase liquid crystal to stabilize the crystal structure of the blue-phase liquid crystal. 
     When no electric field is applied to the blue-phase liquid crystal, the blue-phase liquid crystal changes to a blue-phase state having an optical isotropic property, but not having a double refractive property. When the electric field is applied to the blue-phase liquid crystal, the blue-phase liquid crystal has an optical anisotropic property and a double refractive property. At this point, the electric field is substantially applied in a horizontal direction. The horizontal direction indicates a direction that is parallel to a pair of substrates that face each other with the blue-phase liquid crystal interposed therebetween. The electric field is applied to the blue-phase liquid crystal through electrodes disposed on the substrates. 
     However, the LCD using the blue-phase liquid crystal may have limitations that increase driving voltage and deteriorate light transmittance. 
     Therefore, the electrodes may protrude in a direction crossing the substrates to enhance a horizontal electric field applied to the blue-phase liquid and lower the driving voltage. 
     Although the driving voltage may be gradually reduced as the degree to which the electrodes protrude increases, a cell gap should be increased to secure sufficient light transmittance. The cell gap is a gap between the substrates, which face each other with the blue-phase liquid crystal disposed therebetween. That is, since a region where the electric field is induced exists above the electrodes, the region where the electric field is formed may be gradually reduced as the degree to which the electrodes protrude increases. Therefore, the cell gap should be increased as the degree to which the electrodes protrude increases. If the region where the electric field is formed is not sufficiently secured, the light transmittance may deteriorate. 
     SUMMARY OF THE INVENTION 
     The present invention discloses a display device that may have a reduced driving voltage can be reduced and improved light transmittance. 
     The present invention also discloses a method of manufacturing the display device. 
     Additional features of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. 
     The present invention discloses a display device including a first substrate having first and second electrodes spaced apart from each other, a protrusion pattern portion disposed underneath at least one of the first and second electrodes, and a spacer portion on the same layer as the protrusion pattern portion and made of the same material as the protrusion pattern portion, a second substrate that faces the first substrate and includes a column spacer facing the spacer portion, and a liquid crystal layer disposed between the first and second substrates. The spacer portion and the column spacer function to maintain a gap between the first and second substrates. The liquid crystal layer is in an isotropic state when no electric field is applied, and is in an anisotropic state when an electric field is applied. 
     The present invention also discloses a method of manufacturing a display device including forming at least one thin film transistor on a substrate member, forming a photosensitive organic layer on the substrate member and the thin film transistor, exposing and developing the photosensitive organic layer to form a protrusion pattern and a spacer pattern, and disposing a column spacer facing the spacer portion, wherein the thin film transistor is located between the substrate member and the spacer portion. 
     It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention, and together with the description serve to explain the principles of the invention. 
         FIG. 1  is a layout view of a display device according to an exemplary embodiment of the present disclosure. 
         FIG. 2  is a cross-sectional view taken along line II-II of  FIG. 1 . 
         FIG. 3  shows a process for stabilizing a blue-phase liquid crystal used in the display device of  FIG. 1 . 
         FIG. 4  shows a variation of a blue-phase liquid crystal used for the display device of  FIG. 1  depending on whether an electric field is applied or not. 
         FIG. 5  is a graph showing a relationship between a height of a protrusion pattern portion, a driving voltage, and an effective cell gap. 
         FIG. 6 ,  FIG. 7 ,  FIG. 8 ,  FIG. 9 ,  FIG. 10 , and  FIG. 11  are cross-sectional views showing a method of manufacturing the display device of  FIG. 1  according to an exemplary embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS 
     The invention is described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the invention 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 is thorough, and will fully convey the scope of the invention to those skilled in the art. In the drawings, the size and relative sizes of layers and regions may be exaggerated for clarity. Like reference numerals in the drawings denote like elements. 
     It will be understood that when an element or layer is referred to as being “on” or “connected to” another element or layer, it can be directly on or directly connected to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on” or “directly connected to” another element or layer, there are no intervening elements or layers present. 
     In the accompanying drawings, a display device using amorphous silicon thin film transistors (a-Si TFTs) that are formed through a process using 5 masks is schematically shown. In addition, two TFTs are used for one pixel in the accompanying drawings. The pixel is a minimum unit to display an image. The TFT may be modified in various ways. 
     An exemplary embodiment of the present disclosure will now be described with reference to  FIG. 1  and  FIG. 2 .  FIG. 1  and  FIG. 2  show a display device of an exemplary embodiment of the present disclosure. In  FIG. 2 , a right portion of area A is a cross-sectional view taken along line II-II of  FIG. 1  and area A is a cross-sectional view of an edge of the display device of  FIG. 1 . 
     As shown in  FIG. 1  and  FIG. 2 , a display device  900  includes a first substrate  100 , a second substrate  200 , and a liquid crystal layer  300 . 
     The first substrate  100  includes a first substrate member  110 , a first electrode  191 , a second electrode  192 , a protrusion pattern portion  181 , and a spacer portion  185 . 
     The first and second electrodes  191  and  192  are disposed on the first substrate member  110  and are spaced apart from each other. The first and second electrodes  191  and  192  may have slit patterns that are alternately engaged with each other. 
     The protrusion pattern portion  181  is disposed underneath at least one of the first and second electrodes  191  and  192 . In  FIG. 2 , the protrusion pattern portion  181  is disposed underneath both the first and second electrodes  191  and  192 . The present disclosure, however, is not limited to this configuration. That is, the protrusion pattern portion  181  may be disposed underneath only one of the first and second electrodes  191  and  192 . 
     Since the protrusion pattern portion  181  is disposed underneath the first and second electrodes  191  and  192 , a horizontal electric field may be effectively induced between the first and second electrodes  191  and  192 . The horizontal electric field indicates an electric field that is applied in a horizontal direction that is substantially parallel with the first and second substrates  100  and  200  that face each other with the liquid crystal layer  300  disposed therebetween. That is, since the first and second electrodes  191  and  192  protrude due to the protrusion pattern portion  181  disposed underneath thereof, a horizontal electric field may be effectively induced between the first and second electrodes  191  and  192 . Each of the first and second electrodes  191  and  192  may have a width of 1-10 μm. The first and second electrodes  191  and  192  may be spaced apart from each other by a distance of 3-6 μm. As the distance between the first and second electrodes  191  and  192  is reduced, the performance of the display device may be improved. However, in an actual manufacturing process, the distance between the first and second electrodes  191  and  192  may be limited within a range of 3-6 μm in consideration of a process margin. 
     When the distance between the first and second electrodes  191  and  192  is greater than the width of each of the first and second electrodes  191  and  192 , it may be advantageous in reducing the light transmittance. When the distance between the first and second electrodes  191  and  192  is less than the width of each of the first and second electrodes  191  and  192 , it may be advantageous in reducing the driving voltage. The display device  900  using the blue-phase liquid crystal may have a relatively high driving voltage and thus it may be advantageous to reduce the driving voltage. Therefore, the width of each of the first and second electrodes  191  and  192  may be greater than or equal to the distance between the first and second electrodes  191  and  192 . The present invention, however, is not limited thereto. When it is intended to enhance the light transmittance rather than to reduce the driving voltage, each of the first and second electrodes  191  and  192  may be designed to have a width that is less than the distance between the first and second electrodes  191  and  192 . 
     Each protrusion of the protrusion pattern portion  181  may have a width of 1-10 μm, and the protrusions may be spaced apart from each other by a distance of 3-6 μm. When the protrusion pattern portion  181  is disposed underneath only one of the first and second electrodes  191  and  192 , the distance between the protrusions of the protrusion pattern portion  181  may be outside the range of 3-6 μm. 
     In  FIG. 2 , the protrusion pattern portion  181  has a semi-circular section or a semi-oval section. The present invention, however, is not limited to this. Therefore, the protrusion pattern portion  181  may be designed to have a polygonal section. 
     The first substrate  100  further includes TFTs  101  and  102 , gate lines  121 , and data lines  161   a  and  161   b , all of which are disposed on the first substrate member  110 . 
     The TFTs  101  and  102  will be included to first and second TFTs, respectively. The first TFT  101  is connected to the first electrode  191  and the second TFT  102  is connected to the second electrode  192 . The first and second TFTs  101  and  102  are connected to the common gate line  121 . The first and second TFTs  101  and  102  are further connected to the data lines  161   a  and  161   b , respectively. Therefore, different voltages are applied to the first and second electrodes  191  and  192  and thus the horizontal electric field is generated between the first and second electrodes  191  and  192 . The horizontal electric field indicates an electric field that is induced in a direction that is substantially parallel with the substrates  100  and  200 . The liquid crystal molecules of the liquid crystal layer  300  move according to the horizontal electric field induced between the first and second electrodes  191  and  192 . 
     The spacer portion  185  corresponds to the first and second TFTs  101  and  102 . That is, the first and second TFTs  101  and  102  are disposed between the first substrate member  110  and the spacer portion  185 . The spacer portion  185  planarizes a region above the first and second TFTs  101  and  102 . 
     The protrusion pattern portion  181  and the spacer portion  185  may be made of an organic material. In more detail, the protrusion pattern portion  181  and the spacer portion  185  may be formed by exposing and developing a photosensitive organic layer. 
     In addition, the first substrate  100  further includes a color filter  175 . The color filter  175  is disposed between the first substrate member  110  and the protrusion pattern portion  181 . The color filter  175  functions to provide color to light passing through the liquid crystal layer. 
     The second substrate  200  includes a second substrate member  210  and a column spacer  285  disposed on the second substrate member  210 . The column spacer  285  is disposed to face the spacer portion  185  of the first substrate  100 . The column spacer  285  and the spacer portion  185  stably maintain a gap between the first and second substrates  100  and  200 . 
     The liquid crystal layer  300  includes cross-linked blue-phase liquid crystal. As described above, the liquid crystal layer  300  is disposed between the first and second substrates  100  and  200 . The blue-phase liquid crystal molecules of the liquid crystal layer  300  move according to the horizontal electric field generated between the first and second electrodes  191  and  192 . Since the blue-phase liquid crystal has a relatively narrow operational temperature range, a non-liquid crystal monomer may be added to a low molecular weight liquid crystal that can change to a blue-phase state. Ultraviolet rays are irradiated to the monomer to polymerize the monomer. As a result, a cross-linked blue-phase liquid crystal with a stabilized crystal structure is formed. The cross-linked blue-phase liquid crystal has a network polymer formed in the low molecular weight liquid crystal. That is, the blue-phase liquid crystal is stabilized to have a wide operational range by being polymerized when a monomer added to chiral nematic liquid crystal is hardened. The blue phase is a liquid crystal phase that appears at a temperature range between a cholesteric phase and an isotropic phase. 
     When the liquid crystal layer  300  includes the blue-phase liquid crystal, alignment layers between the first and second substrates  100  and  200  may be omitted. When no electric field is applied to the blue-phase liquid crystal, the blue-phase liquid crystal changes to a blue-phase state with optical isotropic property, but not a double refractive property. When the electric field is applied to the blue-phase liquid crystal, the blue-phase liquid crystal may have both an optical anisotropic property and a double refractive property. As the intensity of the electric field increases, the number of directors aligned in an electric field direction may increase, thereby changing an input polarization state. That is, the blue-phase liquid crystal molecules of the liquid crystal layer  300  may control light transmittance while their alignments change according to the horizontal electric field formed between the first and second electrodes  191  and  192 . 
     Since the blue-phase liquid crystal may have the optical isotropic property when no electric field is applied, the display device  900  may have a normally black mode. That is, when no voltage is applied to the electrodes  191  and  192 , the display device  900  may display black. 
     An acrylate-based monomer, which may be polymerized by heat or ultraviolet rays, may be used as the non-liquid crystal monomer. However, the present invention is not limited thereto. For example, materials including a polarization group such as a vinyl group, an acryloyl group, a fumarate group, and the like may be used as the non-liquid crystal monomer. Meanwhile, an initiator, which may initiate the polymerization of the cross-linking agent, and a monomer may be used as needed. Acetophenone, benzophenone, or the like may be used as the initiator. Chiral dopants may be added to the liquid crystal layer  300  to change the liquid crystal to a chiral nematic phase. 
     A material that can change to the blue-phase state between the chiral phase and the isotropic phase may be used as the low molecular weight liquid crystal. The low molecular weight liquid crystal may include a molecular structure of a biphenyl, a cyclohexyl, or the like. The low molecular weight liquid crystal may have chirality itself or may be made of a material that can change to a cholesteric phase when chiral dopants are added thereto. 
     The following will describe the blue-phase liquid crystal used in the display device  900  of  FIG. 1  and  FIG. 2  in more detail with reference to  FIG. 3  and  FIG. 4 . 
     As shown in  FIG. 3 , the blue-phase liquid crystal is made by stabilizing the blue-phase state up to a room temperature region by forming a photo-linkable polymer when a chiral phase is induced to a positive liquid crystal and the blue phase is formed at about 1 K (absolute temperature). 
     The blue-phase liquid crystal that is stabilized at a wider temperature range by the polymer may have a very large equilibrium constant (K). Therefore, when the electric field is applied to the blue-phase liquid crystal, gray levels can be represented. In addition, when no electric field is applied, the blue-phase liquid crystal has an optical isotropic property. 
     As shown in  FIG. 4 , when no electric field is applied to the blue-phase liquid crystal, the blue-phase liquid crystal changes to the blue-phase state having the optical isotropic property, but not the double refractive property. When the electric field is applied to the blue-phase liquid crystal, the blue-phase liquid crystal has both an optical anisotropic property and a double refractive property. At this point, the electric field is applied to the blue-phase liquid crystal in a direction crossing with a direction in which the light passes through the liquid crystal layer  300 . 
     The blue-phase liquid crystal used in the display device  900  may have a chiral pitch of 300 nm or less because the chiral pitch of the blue-phase liquid crystal should be different from a wavelength of visible light. For example, the blue-phase liquid crystal may have a chiral pitch of 200 nm. For example, since the wavelength of the visible light may be about 350-650 nm, the blue-phase liquid crystal used in the display device  900  may have chiral pitch of 300 nm or less. 
     The blue-phase liquid crystal may have a very high dielectric constant and a very high refractive index. In addition, the blue-phase liquid crystal may be nematic liquid crystal. 
     The protrusion pattern portion  181  may have a height of 1-6 μm. When the height of the protrusion pattern portion is less than 1 μm, the intensity of the horizontal electric field is reduced, which may prevent reduction of the driving voltage. When the height of the protrusion pattern portion is greater than 6 μm, the driving voltage reduction effect may be improved but a minimum gap between the first and second substrates  100  and  200 , which is required to secure sufficient light transmittance, is significantly increased. That is, as the height of the protrusion pattern  181  increases, a space that is defined above the first and second electrodes  191  and  192  and where the electric field is induced is gradually reduced. When the space where the electric field is formed is not sufficiently secured, the light transmittance may deteriorate. 
       FIG. 5  shows variations of a driving voltage and an effective cell gap depending on the height of the protrusion pattern portion. An effective cell gap indicates a minimum gap between the first and second substrates  100  and  200  that can secure proper light transmittance. Referring to  FIG. 5 , as the height of the protrusion pattern portion  181  increases, the driving voltage of the display device  900  may be reduced while the effective cell gap is increased. 
     A height of the spacer portion  185  may be greater than the height of the protrusion pattern portion  181 . That is, the spacer portion  185  is higher than the protrusion pattern portion  181 . In more detail, the height of the spacer portion  185  may be within a range of 1.1-10 μm. 
     A minimum gap that is defined between the first and second substrates  100  and  200  by the spacer portion  185  of the first substrate  100  and the column spacer  285  of the second substrate  200  may be 3 μm or more. The minimum gap between the first and second substrates  100  and  200  may be greater than the height of the protrusion pattern portion  181 . That is, the minimum gap between the first and second substrates  100  and  200  may be set in consideration of a process margin in addition to the effective cell gap determined in accordance with the height of the protrusion pattern portion  181 . 
     Therefore, a relatively large gap may be required between the first and second substrates  100  and  200  depending on the height of the protrusion pattern portion  181 . 
     For example, when the protrusion pattern portion  181  is designed to have a height of about 3 μm to effectively reduce the driving voltage, an effective cell gap of about 5 μm or more may be required. At this point, considering the process margin, a minimum cell gap of about 7 μm or more may be required between the first and second substrates  100  and  200 . 
     That is, the display device  900  using the blue-phase liquid crystal may require a relatively large gap between the substrates  100  and  200 . 
     When the gap between the first and second substrates  100  and  200  is maintained by only the column spacer  285  of the second substrate  200  without using the spacer portion  185  of the first substrate  100 , a bottom area of the column spacer  285  should be increased in proportion to the height of the column spacer  285 . Therefore, an area occupied by the column spacer  285  may significantly increase as the cell gap increases. In this case, an aperture ratio of the display device  900  may be reduced and thus image quality of the display device  900  may deteriorate. 
     However, according to the exemplary embodiment of the present disclosure, the relatively large gap may be stably maintained between the first and second substrates  100  and  200  by forming the spacer portion  185  on the first substrate member  110  and by forming the column spacer  285  on the second substrate member  210  corresponding to the spacer portion  185 . 
     Since the spacer portion  185  on the first substrate  100  may be formed during a process for forming the protrusion pattern portion  181 , the number of processes may not be increased. That is, the spacer portion  185  may be simultaneously formed with the protrusion pattern portion  181  and may include the same material as the protrusion pattern portion  181 . 
     The following will describe the display device  900  in more detail with reference to  FIG. 2 .  FIG. 2  shows a portion around the first TFT  101 . In the following description, only the first TFT  101  is described, but it should be noted that the second TFT  102  may have an identical structure to that of the first TFT  101 . 
     A structure of the first substrate  100  will first be described. 
     The first substrate member  110  may includes a transparent material, such as glass, quartz, ceramic, or plastic. 
     A plurality of gate metal lines including a plurality of gate lines  121 , a plurality of gate electrodes  124  branched from the gate lines  121 , and a plurality of storage electrode lines  128  are disposed on the first substrate  110 . 
     The gate metal lines  121 ,  124 , and  128  may include a metal such as Al, Ag, Cr, Ti, Ta, Mo, and Cu, or an alloy containing at least one of these metals. In  FIG. 2 , each gate metal line  121 ,  124 , and  128  may be a single metal layer. However, the present invention is not limited thereto. For example, each gate metal line  121 ,  124 , and  128  may include multiple layers having a first metal layer including a metal such as Cr, Mo, Ti, and Ta, which has excellent physicochemical properties, or an alloy containing at least one of these metals, and a second metal layer including a Al-based metal or Ag-based metal having low resistivity. In addition to the above metals, various other metals or conductive materials may be used to form the gate metal lines  121 ,  124 , and  128 . In addition, the gate metal lines  121 ,  124 , and  128  may include multiple layers that can be patterned under the same etching conditions. 
     A gate dielectric  130 , which may include silicon nitride (SiN x ), is disposed on the first substrate member  110  to cover the gate metal lines  121 ,  124 , and  128 . 
     The data metal lines including a plurality of data lines  161   a  and  161   b  crossing the gate lines  121 , a plurality of source electrodes  165  branched from the data lines  161   a  and  161   b , and a plurality of drain electrodes  166  spaced apart from the source electrodes  165  are disposed on the gate dielectric  130 . 
     Like the gate metal lines  121 ,  124 , and  128 , the data metal lines  161   a ,  161   b ,  165 , and  166  may include a metal such as Cr, Mo, Al, and Cu, or an alloy containing at least one of these metals, and may be a single layer or may have multiple layers. 
     A semiconductor layer  140  is disposed on a portion of the gate dielectric  130  above the gate electrode  124  to include a portion underneath the source and drain electrodes  165  and  166 . In more detail, at least a portion of the semiconductor layer  140  overlaps the gate, source, and drain electrodes  124 ,  165 , and  166 . The gate, source, and drain electrodes  124 ,  165 , and  166  function as three electrodes of the first TFT  101 . The semiconductor layer  140  between the source and drain electrodes  165  and  166  functions as a channel of the first TFT  101 . 
     In addition, ohmic contacts  155  and  156  may be respectively disposed between the semiconductor layer  140  and the source electrode  165  and between the semiconductor layer  140  and the drain electrode  166  to reduce contact resistances between the semiconductor layer  140  and the source electrode  165  and between the semiconductor layer  140  and the drain electrode  166 . The ohmic contacts  155  and  156  may be made of amorphous silicon and may be highly doped with silicide or n-type impurities. 
     A passivation layer  170 , which may be made of a low dielectric constant material such as a-Si:C:O or a-Si:O:F, an inorganic dielectric material such as silicon nitride or silicon oxide, or an organic material, may be disposed on the gate dielectric  130  through plasma enhanced chemical vapor deposition (PECVD) to cover the data metal lines  161   a ,  161   b ,  165 , and  166 . 
     A color filter  175  having three primary colors is disposed on the passivation layer  170 . The colors of the color filter are not limited to the three primary colors and may be variously formed with one or more colors. The color filter  175  provides color to light passing through the display device  900 . 
     In the exemplary embodiment, the color filter  175  is disposed on the passivation layer  170 . However, the present disclosure is not limited thereto. For example, the color filter  175  may be disposed between the passivation layer  170  and the data metal lines  161   a ,  161   b ,  165 , and  166 . Alternatively, the color filter  175  may be disposed on the second substrate  200  rather than the first substrate  100 . 
     A light blocking member  176  is disposed on a portion of the passivation layer  170  above the TFT  101 . The light blocking member  176  prevents the first TFT  101  from malfunctioning due to light leakage caused by light directed to the channel region of the first TFT  101 . The light blocking member  176  may be omitted as needed. 
     A capping layer  179  is disposed on the color filter  175  and the light blocking member  176 . The capping layer  179  protects the organic layers including the color filter  175 . However, the capping layer  179  may be omitted as needed. The capping layer  179  may be made of a variety of materials including an inorganic material similar to the protective layer  170 . 
     The protrusion pattern portion  181  and the spacer portion  185  are disposed on the capping layer  179 . The protrusion pattern portion  181  and the spacer portion  185  may be made by exposing and developing a photosensitive organic material. However, the present invention is not limited thereto. That is, the protrusion pattern  181  and the spacer portion  185  may be made of a variety of other materials. 
     The protrusion pattern portion  181  includes protrusions that each may have a semi-circular shape section or a semi-oval shape section. However, the present invention is not limited thereto. The protrusions may have a polygonal section. 
     The spacer portion  185  is thicker than the protrusion pattern portion  181 . The spacer portion  185  is disposed above the first TFT  101  to planarize a region above the first TFT  101 . 
     The spacer portion  185  is disposed on an area greater than an area where the column spacer  285  facing the spacer portion  100  is disposed to prevent the column spacer  285  from being misaligned. Therefore, misalignment between the spacer portion  185  and the column spacer  285  may be prevented when the first and second substrates  100  and  200  are assembled with each other. 
     The first and second electrodes  191  and  192  are disposed on the protrusion pattern portion  181 . When the protrusion pattern portion  181  is disposed underneath only one of the first and second electrodes  191  and  192 , the other of the first and second electrodes  191  and  192  is disposed directly on the capping layer  179 . 
     The first electrode  191  is connected to the first TFT  101  and the second electrode  192  is connected to the second TFT  102  (see  FIG. 1 ). The first and second electrodes  191  and  192  may be made of a transparent conductive material, such as indium tin oxide (ITO) and indium zinc oxide (IZO). In more detail, the first electrode  191  includes an electrode portion  1912  and a connecting portion  1911  connecting the electrode portion  1912  to the first TFT  101 . A portion  1915  of the first electrode  191  overlaps the storage electrode line  128  to form a storage capacitor. 
     The passivation layer  170  and the capping layer  179  are provided with a plurality of contact holes  171  and  172  to partly expose the drain electrodes  166 . The contact holes  171  and  172  formed in the passivation layer  170  and the capping layer  179  may extend through the color filter  175  as needed. The first and second electrodes  191  and  192  are coupled to the drain electrodes  166  of the first and second TFTs  101  and  102  through the contact holes  171  and  172 . The color filter  175  has an opening  174  corresponding to the storage electrode line  128 . 
     The alignment of the blue-phase liquid crystal molecules of the liquid crystal layer  300  varies according to the horizontal electric field induced between the first and second electrodes  191  and  192 , controlling light transmittance by the alignment of the blue-phase. 
     The following will describe a structure of the second substrate  200 . 
     The second substrate  200  includes the second substrate member  210  and the column spacer  285 . The second substrate member  210  may be made of a transparent material, such as glass, quartz, ceramic, or plastic. 
     Particularly, the second substrate member  210  may be made of plastic to reduce the weight and thickness thereof. The plastic may be one of a polycarbonate, a polyimide, a polyethersulfone (PES), a polyarylate (PAR), a polyethylene (PAR), a plyethylenenaphthalate (PEN), and a polyethylene terephthalate (PET). However, the present invention is not limited thereto. 
     The column spacer  285  faces the spacer portion  185  of the first substrate  100 . That is, the column spacer  285  and the spacer portion  185  may contact each other to stably maintain the gap between the first and second substrates  100  and  200 . 
     The column spacer  285  may be made by exposing and developing a photosensitive organic material. 
     According to the display device  900  of the exemplary embodiment of the present disclosure, a sufficient gap may be secured between the substrates  100  and  200 , which may reduce the driving voltage and improve light transmittance. 
     A method of manufacturing the display device  900  according to an exemplary embodiment of the present disclosure will be described with reference to  FIG. 6 ,  FIG. 7 ,  FIG. 8 ,  FIG. 9 ,  FIG. 10 , and  FIG. 11 . 
     As shown in  FIG. 6 , the TFT  101  including the gate electrode  124 , the semiconductor layer  140 , the ohmic contacts  155  and  156 , and the drain and source electrodes  166  and  165 , and the passivation layer  170  covering the TFT  101 , are first formed. Here, the structure of the TFT  101  is not limited to the configuration shown in the drawings. The storage electrode line  128  is formed on the same layer as the gate electrode  124  and may be formed of the same material as the gate electrode  124 . 
     Next, as shown in  FIG. 7 , the color filter  175  is formed on the passivation layer  170 . The color filter  175  is provided with the opening  174  corresponding to the storage electrode line  128 . 
     As shown in  FIG. 8 , the light blocking member  176  is formed to cover the TFT  101 . 
     Next, as shown in  FIG. 9 , the capping layer  179  is formed to cover the color filter  175  and the light blocking member  176 , and the contact holes  171  to expose the drain electrode  166  of the TFT  101  are formed through a photolithography process. 
     Next, as shown in  FIG. 10 , the protrusion pattern portion  181  and the spacer portion  185  are formed by applying the photosensitive organic layer on the capping layer  179  and exposing and developing the photosensitive organic layer. The spacer portion  185  is formed to be thicker than the protrusion pattern portion  181 . The protrusion pattern portion  181  may have a height of 1-6 μm. The spacer portion  185  planarizes a region above the TFT  101 . As described above, the spacer portion  185  may be simultaneously formed with the protrusion pattern portion  181  without using an additional process. 
     Next, as shown in  FIG. 11 , the first and second electrodes  191  and  192  are formed on the protrusion pattern portion  181 . In  FIG. 11 , although both the first and second electrodes  191  and  192  are formed on the protrusion pattern portion  181 , the present invention is not limited thereto. That is, only one of the first and second electrodes  191  and  192  may be formed on the protrusion pattern portion  181 . 
     The first and second electrodes  191  and  192  are spaced apart from each other and are connected to the first and second TFTs  101  and  102  through the contact holes  171  and  172 , respectively. The first and second electrodes  191  and  192  may have slit patterns that are alternately engaged with each other. In addition, the first and second electrodes  191  and  192  may have a width of 1-10 μm, and may be spaced apart from each other by a distance of 3-6 μm. 
     According to the display device of the exemplary embodiments of the present disclosure, since a sufficient gap between the substrates may be secured, the driving voltage may be reduced, and light transmittance may be improved. 
     According to the display device manufacturing method of the exemplary embodiment of the present disclosure, since a sufficient gap between the substrates may be secured, the driving voltage of the display device may be reduced, and light transmittance may be improved. 
     It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.