Patent Publication Number: US-9885909-B2

Title: Liquid crystal display and manufacturing method thereof

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a divisional of U.S. patent application Ser. No. 14/261,181, filed on Apr. 24, 2014, which claims priority to and the benefit of Korean Patent Application No. 10-2013-0126048 filed in the Korean Intellectual Property Office on Oct. 22, 2013, the entire contents of which are incorporated herein by reference. 
    
    
     BACKGROUND 
     (a) Field 
     The present disclosure relates to a liquid crystal display and a manufacturing method thereof. 
     (b) Description of the Related Art 
     A liquid crystal display, which is one of the most common types of flat panel displays currently in use, typically includes two sheets of display panels with field generating electrodes (such as a pixel electrode and a common electrode) and a liquid crystal layer interposed therebetween. 
     The liquid crystal display generates an electric field in the liquid crystal layer by applying a voltage to the field generating electrodes. The electric field determines the alignment of liquid crystal molecules in the liquid crystal layer, which controls polarization of incident light, thereby enabling images to be displayed. 
     The liquid crystal display can be manufactured using different methods. For example, a method of forming a pixel unit having a cavity and filling a liquid crystal therein has been developed. Specifically, the method may include forming a sacrificial layer (comprising an organic material and the like) on a lower plate, removing the sacrificial layer after forming a support member thereon, and filling a liquid crystal in the empty space (formed by the removal of the sacrificial layer) through a liquid crystal injection hole. 
     Different types of liquid crystal display devices may possess different display characteristics. For example, a transmissive liquid crystal display including a backlight may have high luminance and high contrast ratio indoors (e.g. inside a building), but low luminance and low contrast ratio outdoors. On the other hand, a reflective liquid crystal display may have good electro-optical characteristics outdoors (by using natural light from the surroundings as a light source), but poor electro-optical characteristic indoors. 
     Accordingly, there is a need for a liquid crystal display combining the above-described advantages of both the transmissive and reflective liquid crystal displays without having their inherent deficiencies. 
     SUMMARY 
     The present disclosure is directed to address at least the above need, by providing a double cell gap structure in a transflective liquid crystal display using sacrificial layers of different thicknesses. 
     According to some embodiments of the inventive concept, a liquid crystal display is provided. The liquid crystal display includes a substrate including a reflective area and a transmissive area; a thin film transistor disposed on the substrate; a pixel electrode disposed on the thin film transistor; and a roof layer disposed facing the pixel electrode, wherein a plurality of microcavities are formed between the pixel electrode and the roof layer, and a liquid crystal material is disposed in the plurality of microcavities, and wherein the reflective area includes a first cell gap, and the transmissive area includes a second cell gap that is different from the first cell gap. 
     In some embodiments, the first cell gap may correspond to a height of the microcavities in the reflective area, and the second cell gap may correspond to a height of the microcavities in the transmissive area. 
     In some embodiments, the first cell gap may be smaller than the second cell gap. 
     In some embodiments, a thickness of the roof layer in the reflective area may be different from a thickness of the roof layer in the transmissive area. 
     In some embodiments, the pixel electrode may include a transparent electrode and a reflective electrode disposed on a first portion of the transparent electrode, and the first portion of the transparent electrode and the reflective electrode may be disposed in the reflective area, and a second portion of the transparent electrode may be disposed in the transmissive area. 
     In some embodiments, each of the reflective area and the transmissive area may correspond to one unit pixel area. 
     In some embodiments, the reflective area may include one of a pixel area adjacent in a horizontal direction and a pixel area adjacent in a vertical direction, and the transmissive area may include the other one of the pixel area adjacent in the horizontal direction and the pixel area adjacent in the vertical direction. 
     In some embodiments, the liquid crystal display may further include a common electrode and a lower insulating layer disposed between the microcavity and the roof layer, wherein the lower insulating layer may be disposed on the common electrode. 
     In some embodiments, the liquid crystal display may further include a capping layer disposed on the roof layer, wherein a liquid crystal injection hole formation region may be disposed between the plurality of microcavities, and the capping layer may be disposed covering the liquid crystal injection hole formation region. 
     In some embodiments, the liquid crystal injection hole formation region may extend in a direction parallel to a gate line connected to the thin film transistor. 
     According to some other embodiments of the inventive concept, a method of manufacturing a liquid crystal display is provided. The method includes forming a thin film transistor on a substrate; forming a pixel electrode, wherein the pixel electrode is connected to a terminal of the thin film transistor; forming a sacrificial layer on the pixel electrode, wherein the sacrificial layer includes a first portion having a first thickness and a second portion having a second thickness; forming a roof layer on the sacrificial layer; forming, by removing the sacrificial layer, a plurality of microcavities having a liquid crystal injection hole; and injecting an alignment material and a liquid crystal material into the plurality of microcavities through the liquid crystal injection hole, wherein the first portion of the sacrificial layer corresponds to a reflective area, and the second portion of the sacrificial layer corresponds to a transmissive area. 
     In some embodiments, the first thickness may correspond to a cell gap of the reflective area, and the second thickness may correspond to a cell gap of the transmissive area. 
     In some embodiments, a thickness of the roof layer in the reflective area may be greater than a thickness of the roof layer in the transmissive area. 
     In some embodiments, forming the sacrificial layer on the pixel electrode may further include forming the first portion and the second portion alternately in a direction of a gate line connected to the thin film transistor. 
     In some embodiments, forming the sacrificial layer on the pixel electrode may further include forming the first portion and the second portion alternately in a direction of a data line connected to the thin film transistor. 
     In some embodiments, the method may further include forming a common electrode and a lower insulating layer on the sacrificial layer before forming the roof layer. 
     In some embodiments, the method may further include forming a capping layer on the roof layer to cover the liquid crystal injection hole. 
     In some embodiments, a liquid crystal injection hole formation region may be formed between the plurality of microcavities, and the capping layer may be formed covering the liquid crystal injection hole formation region. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a plan view illustrating a liquid crystal display according to an exemplary embodiment of the inventive concept. 
         FIG. 2  is a cross-sectional view of the liquid crystal display of  FIG. 1  taken along line II-II. 
         FIG. 3  is a cross-sectional view of the liquid crystal display of  FIG. 1  taken along line III-III. 
         FIG. 4  is a plan view schematically illustrating a reflective area and a transmissive area in the liquid crystal display of  FIG. 1 . 
         FIG. 5  is a plan view illustrating an exemplary embodiment in which the layout of the reflective area and the transmissive area in  FIG. 4  is modified. 
         FIG. 6  is a plan view illustrating another exemplary embodiment in which the layout of the reflective area and the transmissive area in  FIG. 4  is modified. 
         FIGS. 7 to 17  are cross-sectional views illustrating a method of manufacturing a liquid crystal display according to an exemplary embodiment of the inventive concept. 
     
    
    
     DETAILED DESCRIPTION 
     Exemplary embodiments of the inventive concept will be described in detail herein with reference to the accompanying drawings. As those skilled in the art would realize, the described embodiments may be modified in various ways without departing from the spirit or scope of the inventive concept. 
     In the drawings, the thickness of layers, films, panels, regions, etc., may be exaggerated for clarity. It will be understood that when a layer is referred to as being “on” another layer or substrate, it can be disposed directly on the other layer or substrate, or with one or more intervening layers or substrates being present. Like reference numerals designate like elements throughout the specification. 
       FIG. 1  is a plan view illustrating a liquid crystal display according to an exemplary embodiment of the inventive concept.  FIG. 2  is a cross-sectional view of the liquid crystal display of  FIG. 1  taken along line II-II.  FIG. 3  is a cross-sectional view of the liquid crystal display of  FIG. 1  taken along line  FIG. 4  is a plan view schematically illustrating a reflective area and a transmissive area in the liquid crystal display of  FIG. 1 . 
     The liquid crystal display includes a plurality of pixels PX disposed in a display area DA, which will be described in detail with reference to  FIGS. 1 to 3 . 
     Referring to  FIGS. 1 to 3 , a gate line  121  and a storage electrode line  131  are formed on a substrate  110 . The substrate  110  may be formed of transparent glass, plastic, or the like. The gate line  121  includes a gate electrode  124 . The storage electrode line  131  transfers a predetermined voltage (such as a common voltage Vcom), and extends in a substantially horizontal direction. The storage electrode line  131  also includes a pair of vertical portions  135   a  extending substantially perpendicular to the gate line  121 , and a pair of horizontal portions  135   b  connecting the ends of the vertical portions  135   a . The vertical and horizontal portions  135   a  and  135   b  of the storage electrode line  131  are formed surrounding a pixel electrode  191 . 
     A gate insulating layer  140  is formed on the gate line  121  and the storage electrode line  131 . Semiconductor layers ( 151  and  154 ) and data conductors ( 171 ,  173 , and  175 ) are formed on the gate insulating layer  140 . Referring to  FIG. 3 , a semiconductor layer  151  is formed on the gate insulating layer  140 , and a data line  171  is formed on the semiconductor layer  151 . Referring to  FIG. 2 , a semiconductor layer  154  is formed on the gate insulating layer  140 , and a source electrode  173  and a drain electrode  175  are formed on the semiconductor layer  154 . The data line  171  is connected to the source electrode  173 . 
     In some embodiments, a plurality of ohmic contacts (not shown) may be formed on the respective semiconductor layers  151  and  154 , and between the data line  171  and the source/drain electrodes  173  and  175 . 
     The gate electrode  124 , the source electrode  173 , and the drain electrode  175 , together with the semiconductor layer  154 , collectively constitute a thin film transistor Q. A channel of the thin film transistor Q is formed in a portion of the semiconductor layer  154  between the source electrode  173  and the drain electrode  175 . 
     A first interlayer insulating layer  180   a  is formed on the data conductors  171 ,  173 , and  175 , and on an exposed portion of the semiconductor layer  154 . The first interlayer insulating layer  180   a  may include an inorganic insulator (such as silicon nitride (SiNx) or silicon oxide (SiOx)) or an organic insulator. 
     A color filter  230  and a plurality of light blocking members are formed on the first interlayer insulating layer  180   a . The plurality of light blocking members include a horizontal light blocking member  220   a  and a vertical light blocking member  220   b.    
     The light blocking members  220   a  and  220   b  are formed in a lattice structure of the color filter  230 . The lattice structure includes openings corresponding to an area for displaying images. The light blocking members  220   a  and  220   b  are formed of an opaque material (that does not transmit light). The light blocking members  220   a  and  220   b  are formed in the openings of the color filter  230 . In particular, the horizontal light blocking member  220   a  is formed in a direction parallel to the gate line  121 , and the vertical light blocking member  220   b  is formed in a direction parallel to the data line  171 . 
     The color filter  230  may display one of the primary colors (such as the three primary colors red, green, and blue). However, the color filter  230  need not be limited to the three primary colors red, green, and blue. In some embodiments, the color filter  230  may display one of cyan, magenta, yellow, and white-based colors. The color filter  230  may be formed of a material capable of displaying a different color for every adjacent pixel. 
     A second interlayer insulating layer  180   b  is formed on the color filter  230  and the light blocking members  220   a  and  220   b , covering the color filter  230  and the light blocking members  220   a  and  220   b . The second interlayer insulating layer  180   b  may include an inorganic insulator (such as silicon nitride (SiNx) or silicon oxide (SiOx)) or an organic insulator. As shown in  FIG. 2 , a step is created due to a thickness difference between the color filter  230  and the light blocking members  220   a  and  220   b . Nevertheless, the effect of the step on surface planarity can be mitigated by forming the second interlayer insulating layer  180   b  over the step. 
     A contact hole  185  exposing the drain electrode  175  is formed in the color filter  230 , the light blocking members  220   a , and the interlayer insulating layers  180   a  and  180   b.    
     The pixel electrode  191  is formed on the second interlayer insulating layer  180   b.    
     The pixel electrode  191  may be formed having a quadrangle shape. The pixel electrode  191  includes a plurality of horizontal stems  192   a  and  194   a , and a plurality of vertical stems  192   b  and  194   b  crossing the horizontal stems  192   a  and  194   a . Further, the pixel electrode  192  is divided into four subregions by the horizontal stems  192   a  and  194   a  and the vertical stems  192   b  and  194   b , and each subregion includes a plurality of minute branches  192   c  and  194   c . In some embodiments, the pixel electrode  191  may further include an outer stem surrounding the pixel electrode  191 . 
     The minute branches  192   c  of the pixel electrode  191  form an angle of approximately 40° to 45° with the gate line  121  or the horizontal stem  192   a . Also, the minute branches of two adjacent subregions may be perpendicular to each other. Furthermore, a distance between the minute branches  192   c  and  194   c  may vary with an increase in a linewidth of the minute branches. 
     The pixel electrode  191  includes an extension  197  connected at lower ends of the vertical stems  192   b  and  194   b . The extension  197  has a larger area than the vertical stems  192   b  and  194   b . The pixel electrode  191  is physically and electrically connected with the drain electrode  175  through the contact hole  185  at the extension  197 , so as to receive a data voltage from the drain electrode  175 . 
     In some embodiments, the pixel electrode  191  includes a transparent electrode  192  and a reflective electrode  194  disposed on a portion of the transparent electrode  192 . Accordingly, a transflective liquid crystal display is formed, comprising a reflective area RA and a transmissive area TA formed on the substrate  110 . 
     In the reflective area RA, the pixel electrode  191  includes the transparent electrode  192  and the reflective electrode  194  disposed on the portion of the transparent electrode  192 . In the transmissive area TA, the transparent electrode  192  may be formed as the pixel electrode  191 . The transparent electrode  192  may be formed of a transparent conductive material (such as ITO or IZO), and the reflective electrode  194  may be formed of a reflective metal (such as aluminum, silver, chromium, or an alloy thereof). In some embodiments (not illustrated), the reflective electrode  194  may have a dual-layer structure including a low-resistive reflective upper layer and a lower layer. The low-resistive reflective upper layer may be formed of aluminum, silver, or an alloy thereof. The lower layer may be formed of a material having excellent contact characteristics with ITO or IZO (such as molybdenum-based metals, chromium, tantalum, or titanium). 
     Although not illustrated in the figures, an upper surface of the second interlayer insulating layer  180   b  disposed at the portion corresponding to the reflective area RA may have a curved surface. Also, the transparent electrode  192  and the reflective electrode  194  disposed on the second interlayer insulating layer  180   b  may be curved along the upper surface of the second interlayer insulating layer  180   b.    
     In the transmissive area TA, light that is incident from a rear side of the substrate  110  passes through liquid crystal molecules  310  of a microcavity  305 , and is then emitted to a front side (towards a capping layer  390 ), thereby displaying an image. 
     In the reflective area RA, external light that is input from the front side enters into the microcavity  305  and is reflected by the reflective electrode  194 . The reflected light then passes through the liquid crystal molecules  310  of the microcavity  305  again and is emitted to the front side, thereby displaying the image. In this case, the curved surface of the reflective electrode  194  induces diffused reflection of light, so as to prevent a phenomenon in which an object is reflected on the screen. 
     In some embodiments, the reflective area RA and the transmissive area TA may each include one or more unit pixel areas. Referring to  FIGS. 1 and 4 , the transmissive area TA may include a unit pixel area disposed on an upper left quadrant and a unit pixel area disposed on a lower right quadrant diagonal to the upper left quadrant. The reflective area RA may include a unit pixel area disposed on a lower left quadrant and a unit pixel area disposed on an upper right quadrant diagonal to the lower left quadrant. Although  FIGS. 1 and 4  illustrate 2×2 pixel areas, it should be understood that the layout of the reflective area RA and the transmissive area TA described above (i.e. the 2×2 pixel areas) may be repeated across the entire pixel areas. 
     Furthermore, the thin film transistor Q and the pixel electrode  191  described above are merely exemplary. In some embodiments, a structure of the thin film transistor Q and a design of the pixel electrode  191  may be modified to improve side visibility. 
     A lower alignment layer  11  is formed on the pixel electrode  191 . The lower alignment layer  11  may correspond to a vertical alignment layer. The lower alignment layer  11  serves as a liquid crystal alignment layer, and may be formed of materials such as polyamic acid, polysiloxane, polyimide, or the like. 
     An upper alignment layer  21  is disposed at a portion facing the lower alignment layer  11 , and the microcavity  305  is formed between the lower alignment layer  11  and the upper alignment layer  21 . A liquid crystal material including the liquid crystal molecules  310  is injected into the microcavity  305  through a liquid crystal injection hole  307 . The microcavity  305  may be formed in a column direction, that is, a vertical direction of the pixel electrode  191 . In some embodiments, the alignment material (for forming the alignment layers  11  and  21 ) and the liquid crystal material (including the liquid crystal molecules  310 ) may be injected into the microcavity  305  via capillary force. 
     In some embodiments, a height of a first cell gap in the reflective area RA may be different from a height of a second cell gap in the transmissive area TA. For example, the first cell gap may correspond to a first height d1 of the microcavity  305  in the reflective area RA, the second cell gap may correspond to a second height d2 of the microcavity  305  in the transmissive area TA, and the first cell gap may be smaller than the second cell gap such that d1 is less than d2. 
     In some embodiments, the reflective area RA may be designed for λ/4 wavelengths and the transmissive area TA may be designed for λ/2 wavelengths, so as to equalize the polarization states of light reaching a last polarizer in the reflective area RA and the transmissive area TA. Specifically, the reflective area RA and the transmissive area TA may be designed for λ/4 and λ/2 wavelengths, respectively, by setting the height of the first cell gap of the reflective area RA (d1) to be ½ of the height of the second cell gap of the transmissive area TA (d2). 
     The microcavity  305  is divided in a vertical direction by a plurality of liquid crystal injection hole formation regions  307 FP disposed at the portion overlapping with the gate line  121 . As such, a plurality of microcavities  305  are formed in a direction in which the gate line  121  extends. Each of the microcavities  305  may correspond to one or two or more pixel areas, and the pixel areas may correspond to the area for displaying an image. 
     A common electrode  270  and a lower insulating layer  350  are disposed on the upper alignment layer  21 . The common electrode  270  receives a common voltage and generates an electric field together with the pixel electrode  191  (to which the data voltage is applied). The electric field determines the tilt directions of the liquid crystal molecules  310  disposed in the microcavity  305  between the two electrodes  270  and  191 . The common electrode  270  and the pixel electrode  191  collectively form a capacitor to maintain the applied voltage even after the thin film transistor is turned off. The lower insulating layer  350  may be formed of silicon nitride (SiNx) or silicon oxide (SiO2). 
     In some embodiments, the common electrode  270  is formed on the microcavity  305 . In some other embodiments, the common electrode  270  may be formed below the microcavity  305  and thus the liquid crystal may be driven according to an in-plane switching mode. 
     A roof layer  360  is disposed on the lower insulating layer  350 . The roof layer  360  serves to support the microcavity  305 . As previously described, the microcavity  305  is formed as a space between the pixel electrode  191  and the common electrode  270 . The roof layer  360  may be formed of a photoresist or other organic materials. In some embodiments, a thickness of the roof layer  360  may vary according to the cell gaps of the reflective area RA and the transmissive area TA. For example, a thickness of a portion of the roof layer  360  corresponding to the reflective area RA (having a small cell gap) may be greater than a thickness of another portion of the roof layer  360  corresponding to the transmissive area TA (having a large cell gap). 
     An upper insulating layer  370  is disposed on the roof layer  360 . The upper insulating layer  370  may contact an upper surface of the roof layer  360 . The upper insulating layer  370  may be formed of silicon nitride (SiNx) or silicon oxide (SiO2). 
     In some embodiments, the capping layer  390  is disposed in the liquid crystal injection hole formation region  307 FP covering the liquid crystal injection hole  307  of the microcavity  305 . The capping layer  390  may include an organic material or an inorganic material. 
     In some embodiments (for example, as illustrated in  FIG. 3 ), a partition wall formation portion PWP is disposed between microcavities  305  adjacent to each other in a horizontal direction. The partition wall formation portion PWP may extend in a same direction as the data line  171 , and may be covered by the roof layer  360 . The lower insulating layer  350 , the common electrode  270 , the upper insulating layer  370 , and the roof layer  360  are disposed in the partition wall formation portion PWP. The partition wall formation portion PWP serves as a partition wall structure to partition or define the microcavity  305 . In some embodiments, a partition wall structure (such as the partition wall formation portion PWP) between the microcavities  305  may allow the liquid crystal display to be more flexible. Accordingly, in those embodiments, the heights of the cell gaps can be more uniformly maintained, and the stress generated in the display is small even when the substrate  110  is bent. 
       FIG. 5  is a plan view illustrating an exemplary embodiment in which the layout of the reflective area and the transmissive area in  FIG. 4  is modified. 
     Referring to  FIG. 5 , the reflective area RA or transmissive area TA may be disposed along a direction in which the gate line  121  extends, and the reflective area RA and the transmissive area TA may be alternately disposed along a direction in which the data line  171  extends. 
       FIG. 6  is a plan view illustrating another exemplary embodiment in which the layout of the reflective area and the transmissive area in  FIG. 4  is modified. 
     Referring to  FIG. 6 , the reflective area RA or transmissive area TA may be disposed along a direction in which the data line  171  extends, and the reflective area RA and the transmissive area TA may be alternately disposed along a direction in which the gate line  121  extends. 
     Next, a method of manufacturing a liquid crystal display according to an exemplary embodiment of the inventive concept will be described with reference to  FIGS. 7 to 17 . Specifically,  FIGS. 7, 9, 11, 13, 14, and 16  depict cross-sectional views of the liquid crystal display of  FIG. 1  taken along line II-II, and  FIGS. 8, 10, 12, 15, and 17  depict cross-sectional views of the liquid crystal display of  FIG. 1  taken along line at different stages of manufacturing. 
     Referring to  FIGS. 1, 7, and 8 , the gate line  121  is formed extending in a horizontal direction on the substrate  110 , the gate insulating layer  140  is formed on the gate line  121 , the semiconductor layers  151  and  154  are formed on the gate insulating layer  140 , and the source electrode  173  and the drain electrode  175  are formed on the semiconductor layer  154 . The data line  171  is formed on the semiconductor layer  151 , and is connected to the source electrode  173 . Also, the data line  171  may be formed crossing the gate line  121  and extending in a vertical direction. 
     Next, the first interlayer insulating layer  180   a  is formed on the data conductors (source electrode  173 , drain electrode  175 , and data line  171 ) and on the exposed portion of the semiconductor layer  154 . 
     Next, the color filter  230  is formed on the first interlayer insulating layer  180   a  at a position corresponding to the pixel area. The light blocking members  220   a  and  220   b  are formed in the openings between the color filters  230 . 
     Next, the second interlayer insulating layer  180   b  is formed on the color filter  230  and the light blocking members  220   a  and  220   b , covering the color filter  230  and the light blocking members  220   a  and  220   b . The contact hole  185  is formed in the second interlayer insulating layer  180   b , and allows the pixel electrode  191  to be electrically and physically connected to the drain electrode  175 . The upper surface of the second interlayer insulating layer  180   b  disposed at a portion of the reflective area RA may be formed having a curved surface (not shown). 
     Next, the pixel electrode  191  is formed on the second interlayer insulating layer  180   b.    
     In the reflective area RA, the pixel electrode  191  includes the transparent electrode  192  and the reflective electrode  194  disposed on a portion of the transparent electrode  192 . In the transmissive area TA, the pixel electrode  191  is formed as the transparent electrode  192 . 
     Next, a sacrificial layer  300  is formed on the pixel electrode  191 . As illustrated in  FIG. 8 , an open portion OPN is formed in the sacrificial layer  300 . The open portion OPN is formed in a direction parallel to the data line  171 . Next, as illustrated in  FIG. 10 , the common electrode  270 , the lower insulating layer  350 , the roof layer  360 , and the upper insulating layer  370  are formed in the open portion OPN so as to form the partition wall formation portion PWP. 
     In some embodiments, the sacrificial layer  300  is formed having different thicknesses in the reflective area RA and the transmissive area TA. To form the sacrificial layer  300  having different thicknesses, a slit mask or a halftone mask may be used. 
     Referring to  FIGS. 9 and 10 , the common electrode  270 , the lower insulating layer  350 , and the roof layer  360  are sequentially formed on the sacrificial layer  300 . The roof layer  360  may be removed in a region corresponding to the horizontal light blocking member  220   a  disposed between adjacent pixel areas in the vertical direction using a photolithography process. As a result, a portion of the lower insulating layer  350  corresponding to the horizontal light blocking member  220   a  is exposed by the opening in the roof layer  360 . As previously described, the common electrode  270 , the lower insulating layer  350 , and the roof layer  360  are formed in the open portion OPN of the vertical light blocking member  220   b , so as to form the partition wall formation portion PWP. 
     The roof layer  360  has a substantially greater thickness than the common electrode  270  or the lower insulating layer  350 . An interlayer step is thus created between the reflective area RA and the transmissive area TA due to the sacrificial layer  300  having different thicknesses. As a result, the thickness of the roof layer  360  in the reflective area RA may be greater than the thickness of the roof layer  360  in the transmissive area TA (as illustrated in  FIG. 9 ). 
     Referring to  FIGS. 11 and 12 , the upper insulating layer  370  is formed covering the roof layer  360  and the exposed portion of the lower insulating layer  350 . 
     Referring to  FIG. 13 , the upper insulating layer  370 , the lower insulating layer  350 , and the common electrode  270  are partially removed by dry-etching the upper insulating layer  370 , the lower insulating layer  350 , and the common electrode  270  to form the liquid crystal injection hole formation region  307 FP. In this case, the upper insulating layer  370  may have a structure covering the side of the roof layer  360 , but is not limited thereto. For example, in some other embodiments, the upper insulating layer  370  covering the side of the roof layer  360  may be removed to expose the side of the roof layer  360 . 
     Referring to  FIGS. 14 and 15 , the sacrificial layer  300  is removed from the liquid crystal injection hole formation region  307 FP by an oxygen (O2) ashing process or a wet-etching method, thereby forming the microcavity  305  with the liquid crystal injection hole  307 . The microcavity  305  is an empty space that is formed when the sacrificial layer  300  is removed. 
     Referring to  FIGS. 16 and 17 , the alignment layers  11  and  21  are formed on the pixel electrode  191  and the common electrode  270  by injecting the aligning material through the liquid crystal injection hole  307 . The aligning material includes a solid and a solvent. Thereafter, a bake process is performed so as to drive the solvent from the aligning material. 
     Next, the liquid crystal material including the liquid crystal molecules  310  is injected into the microcavity  305  through the liquid crystal injection hole  307  using an inkjet method and the like. 
     Thereafter, the capping layer  390  is formed on the upper insulating layer  370  to cover the liquid crystal injection hole  307  and the liquid crystal injection hole formation region  307 FP, thus forming the liquid crystal display illustrated in  FIGS. 2 and 3 . 
     While this inventive concept has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the inventive concept is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.