Patent Publication Number: US-8115893-B2

Title: Liquid crystal display device with reflection and transmission regions

Description:
This is a divisional application of U.S. patent application Ser. No. 11/143,587, filed Jun. 3, 2005 now U.S. Pat. No. 7,312,843, and further claims the benefit of the Korean Patent Application No. P2004-41136 filed in Korea on Jun. 5, 2004, both of which are hereby incorporated by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a liquid crystal display device, and more particularly, to a transflective thin film transistor substrate and method of fabricating the same. 
     2. Description of the Related Art 
     Liquid crystal display devices are generally classified into a transmissive type where a picture is displayed using light incident from a backlight unit, and a reflective type where a picture is displayed by reflecting external light such as a natural light. However, the power consumption of the backlight unit is high in the transmissive type, and the reflective type depends on the external light so that it cannot display a picture in a dark environment. 
     To resolve this problem, a transflective liquid crystal display device is increasingly being used, wherein the transflective liquid crystal can be selected to be in a transmissive mode where the backlight unit is used or in a reflective mode where the external light is used. The transflective liquid crystal display device operates in the reflective mode if the external light is sufficient and in the transmissive mode if the external light is not sufficient, thereby reducing the power consumption more than the transmissive liquid crystal display device but not being restricted by external light levels unlike the reflective liquid crystal display device. 
     Generally, a transflective liquid crystal display panel of the related art, as shown in  FIG. 1 , includes a color filter substrate and a thin film transistor substrate which are bonded together with a liquid crystal layer (not shown), and a backlight unit  60  arranged behind the thin film transistor substrate. Each pixel of the transflective liquid crystal display panel is divided into a reflective area where a reflective electrode  28  is formed, and a transmissive area where the reflective electrode  28  is not formed. 
     The color filter substrate includes an upper substrate  52 , a black matrix (not shown), a color filter  54  formed on the upper substrate  52 , a common electrode  56 , and an alignment film (not shown) formed thereover. The thin film transistor substrate includes a lower substrate  2 , a gate line  4 , a data line (not shown) formed on the lower substrate  2  crossing the gate line  4  to define each pixel area, a thin film transistor connected to the gate line  4  and the data line, a pixel electrode  32  formed at the pixel area and connected to the thin film transistor; and a reflection electrode  28  formed at a reflection area of each pixel to overlap the pixel electrode. 
     The thin film transistor includes a gate electrode  6  connected to the gate line  4 ; a source electrode  16  connected to the data line; a drain electrode  18  facing the source electrode  16 ; an active layer  10  overlapping the gate electrode  6  with a gate insulating film  8  therebetween to form a channel between the source and drain electrodes  16  and  18 ; and an ohmic contact layer  12  to make an ohmic contact with the active layer  10 , the source electrode  16 , and the drain electrode  18 . The thin film transistor responds to the scan signal of the gate line  4 , thereby causing a video signal on the data line to be charged and maintained on the pixel electrode  32 . 
     The reflection electrode  28  reflects an external light that is incident through a color filter substrate toward the color filter substrate. At this moment, the surface of an organic film  24  formed under the reflection electrode  28  has an embossing shape, and the reflection electrode  28  on top of the organic film  24  also has the embossing shape, thereby increasing its reflection efficiency due to its dispersion effect. 
     The pixel electrode  32  is connected via an upper storage electrode  20  to the drain electrode of the thin film transistor, and the pixel electrode  32  generates a potential difference with a common electrode  56  by the pixel signal supplied through the thin film transistor. The potential difference causes liquid crystal molecules having dielectric anisotropy to rotate, thereby controlling the transmissivity of the light that passes through a liquid crystal layer of each of the reflection area and a transmission area, and changing its brightness in accordance with the video signal. 
     In this case, a transmission hole  36  is formed in the relatively thick organic film  24  at a transmission area so that the length of the light path going through the liquid crystal layer is the same in the reflection area as in the transmission area. As a result, a path that ambient light incident at the reflection area, i.e., a reflection light RL, goes through the liquid crystal layer, then through the reflection electrode  28 , and then through the liquid crystal layer in the liquid crystal layer is the same in length as a path that the transmission light TL of a backlight unit  60 , which is incident at the transmission area going through the liquid crystal layer. Thus, the transmission efficiency becomes the same in both of the reflection mode and the transmission mode. 
     The thin film transistor substrate further includes a storage capacitor connected to the pixel electrode  32  to maintain the video signal supplied to the pixel electrode  32  stable. The storage capacitor is formed with an upper storage electrode  20  overlapping a storage line  40  with a gate insulating film  8  therebetween. Here, wherein the upper storage electrode  20  is extended from the drain electrode  18  to connect to the pixel electrode  32  via a contact hole  34 . The ohmic contact layer  12  and the active layer  10  further overlap under the upper storage electrode  20  in the process. 
     The thin film transistor substrate further includes a first passivation film  22  between the thin film transistor and the organic film  24 ; a second passivation film  26  between the organic film  24  and the reflection electrode  28 ; and a third passivation film  30  between the reflection electrode  28  and the pixel electrode  32 . Accordingly, the contact hole  34  penetrates the first to the third passivation films  22 ,  26  and  30 , the organic film  24  and the reflection electrode  28  so that the pixel electrode  32  is connected to the upper storage electrode  20 . 
     In such a transflective liquid crystal display panel, the thin film transistor substrate includes the semiconductor process and requires a plurality of mask processes. Thus, its manufacturing process is complicated so that it significantly increases the liquid crystal display panel manufacturing cost. 
     Hereinafter, a fabricating method of the transflective thin film transistor substrate according to the related art will be described in reference with  FIGS. 2A to 2F . As shown in  FIG. 2A , in a first mask process, a gate pattern including the gate line  4 , the gate electrode  6 , and the storage line  40  is formed on the lower substrate  2 . 
     A gate metal layer is formed on the lower substrate  2  by a deposition method such as sputtering. Subsequently, the gate metal layer is patterned by a photolithography process using a first mask and an etching process, thereby forming the gate pattern including the gate line  4 , the gate electrode  6 , and the storage line  40 . The gate metal layer is a single layered or double layered metal, such as Al, Mo, or Cr. 
     As shown in  FIG. 2B , the gate insulating film  8  is formed on the substrate  2  having the gate pattern. On the substrate  2  having the gate insulating film  8 , a semiconductor pattern having the active layer  10  and the ohmic contact layer  12  formed, and a source/drain pattern having the data line, the source electrode  16 , the drain electrode  18  and the upper storage electrode  20  are stacked by the second mask process. 
     The gate insulating film  8 , an amorphous silicon layer, an amorphous silicon layer with impurities doped thereto, and the source/drain metal layer are sequentially formed on the lower substrate  2  where the gate pattern is formed. The gate insulating film  8  is formed of an inorganic insulating material such as silicon oxide SiOx or silicon nitride SiNx, and the source/drain metal layer is the single layered or double layered structure of the metal such as Al, Mo or the like. 
     A photoresist pattern is formed on top of the source/drain metal layer by a photolithography process using a second mask. In this case, a diffractive exposure mask having a diffractive exposure portion at a channel of the thin film transistor is used as the second mask. Thus, the photoresist pattern of the channel has a lower height than the source/drain pattern portion. Subsequently, the source/drain metal layer is patterned by a wet etching process using the photoresist pattern to form the source/drain pattern that includes the data line, the source electrode  16 , the drain electrode  18  integrated with the source electrode  16 , and the storage electrode  20 . Then, the amorphous silicon layer doped with the impurities and the amorphous silicon layer are simultaneously patterned by a dry etching process using the same photoresist pattern, thereby forming the ohmic contact layer  12  and the active layer  10 . After removing the photoresist pattern having relatively low height at the channel by an ashing process, the source/drain pattern and the ohmic contact layer  12  of the channel are etched by a dry etching process. Accordingly, the active layer  10  of the channel is exposed to separate the source electrode  16  from the drain electrode  18 . Subsequently, the photoresist pattern remaining on the source/drain pattern is removed by a stripping process. 
     As shown in  FIG. 2C , a first passivation film  22  is formed on the gate insulating film  8  where the source/drain pattern is formed, and an organic film  24  is formed on top thereof by a third mask process. Here, the organic film  24  has a contact hole  34  and a transmission hole  36  with the embossing shaped surface. 
     The first passivation film  22  and the organic film  24  are sequentially formed on the gate insulating film  8  where the source/drain pattern is formed. The first passivation film  22  is formed of the same inorganic insulating material as the gate insulating film  8 , and the organic film  24  is of a photosensitive organic material, such as an acrylic resin. 
     Then, the organic film  24  is patterned by a photolithography process using the third mask, thereby forming an open hole  35  and the transmission hole  36  which penetrate the organic film  24  in correspondence to the transmission portion of the third mask. At this moment, the third mask has a structure where a shielding portion and a diffractive exposure portion repeat at the rest area except for the transmission portion. The organic film  24  remaining in correspondence thereto is patterned to have a structure that a shielding area (projected portion) and a diffractive exposure area (groove portion) having a stepped difference are repeated. Subsequently, the organic film  24  where the projected portion and the groove portion are repeated is fired so that the surface of the organic film  24  has the embossing shape. 
     As shown in  FIG. 2D , a second passivation film  26  is formed on the organic film  24  that has the embossing shape, and the reflection electrode  28  is formed on top thereof by a fourth mask process. The second passivation film  26  and the reflective metal layer are deposited to maintain their embossing shape on top of the organic film  24  that has the embossing surface. The second passivation film  26  is formed of an inorganic insulating material such as the first passivation film  22 , and the reflective metal layer is formed of a metal such as AlNd or the like, of which the reflectivity is high. Subsequently, the reflective metal layer is patterned by a photolithography process using a fourth mask and the etching process to form the reflection electrode  28 . Here, the reflection electrode is independent of every pixel and is opened at the transmission hole  36  and the open hole  35  of the organic film  24 . 
     As shown in  FIG. 2E , a third passivation film  30  covering the reflection electrode  28  is formed by a fifth mask process, and the contact hole  34  penetrating the first to third passivation films  22 ,  26 ,  30  is formed. The third passivation film  30  covering the reflection electrode  28  is formed and the contact hole  34  is formed by a photolithography process using a fifth mask and the etching process. Here, the contact hole  34  penetrates the first to third passivation films  22 ,  26 ,  30  at the open hole  35  of the organic film  24 . The contact hole  34  exposes the drain electrode  18  and the upper storage electrode  20 . The third passivation film  30  is formed of the same inorganic insulating material as the second passivation film  26 . 
     As shown in  FIG. 2F , a pixel electrode  32  is formed on the third passivation film  30  using a sixth mask process. A transparent conductive layer is formed on the third passivation film  30  by the deposition method such as sputtering, and the transparent conductive layer is patterned by a photolithography process using a sixth mask and the etching process to form the pixel electrode  32  at each pixel area. The pixel electrode  32  is connected to the upper storage electrode  20  through the contact hole  34 . The transparent conductive layer is formed of indium-tin-oxide ITO. 
     In this way, the related art transflective thin film transistor substrate is formed by six mask processes, thereby complicating its manufacturing process is complicated. 
     SUMMARY OF THE INVENTION 
     Accordingly, the present invention is directed to a liquid crystal display device and fabricating method thereof that substantially obviates one or more of the problems due to limitations and disadvantages of the related art. 
     An object of the present invention to provide a transflective thin film transistor substrate and a method of fabricating the same with a simplified process. 
     Additional features and advantages 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 objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings. 
     To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, a liquid crystal display device comprises a first substrate a gate line on the first substrate; a first insulation film on the gate line; a data line crossing the gate line such that the data line and the gate line define a pixel region with a transmission area and a reflection area; a thin film transistor connected to the gate line and the data line; a storage capacitor including a storage line crossing the data line, and an upper storage electrode being connected to the thin film transistor and overlapping the storage line; a second insulation film on the thin film transistor, a transmission hole being defined through the second insulation film; a reflection electrode disposed on the second insulation film in the reflection area and connected to a portion of the upper storage electrode through the transmission hole; a pixel electrode disposed in the pixel region and connected to the reflection electrode; a second substrate facing the first substrate; and a liquid crystal layer disposed between the first and second substrates. 
     In another aspect, a method of fabricating a liquid crystal display device comprises forming a gate pattern on a first substrate using a first mask, the gate pattern including a gate line, a gate electrode connected to the gate line, and a storage line; forming a first insulation film on the gate pattern, a semiconductor pattern on the first insulation film, and a source/drain pattern having a data line, a source electrode, a drain electrode, and an upper storage electrode using a second mask, the data and gate lines crossing each other to define a pixel region with a transmission area and a reflection area; forming a second insulation film on the source/drain pattern using a third mask, the second insulation film defining a transmission hole through the second insulation film; forming a reflection electrode in the reflection area using a fourth mask, the reflection electrode being connected to a portion of the upper storage electrode through the transmission hole; forming a third insulation film on the reflection electrode and a pixel electrode using a fifth mask, the pixel electrode being connected to the reflection electrode; and joining the first substrate with a second substrate and disposing a liquid crystal layer between the first and second substrates. 
     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. In the drawings: 
         FIG. 1  is a sectional view illustrating a portion of a related art transflective liquid crystal display panel; 
         FIGS. 2A to 2F  are sectional views explaining sequentially a fabricating method of the transflective thin film transistor substrate shown in  FIG. 1 ; 
         FIG. 3  is a plane view partially illustrating a transflective thin film transistor substrate according to an embodiment of the present invention; 
         FIG. 4  is a sectional view illustrating the transflective thin film transistor substrate taken along lines II-II′, III-III, IV-IV′ of  FIG. 3 ; 
         FIGS. 5A and 5B  are a plane view and a sectional view describing a first mask process of the transflective thin film transistor substrate according to the present invention; 
         FIGS. 6A and 6B  are a plane view and a sectional view describing a second mask process of the transflective thin film transistor substrate according to the present invention; 
         FIGS. 7A and 7E  are sectional views describing a second mask process according to the present invention; 
         FIGS. 8A and 8B  are a plane view and a sectional view describing a third mask process of the transflective thin film transistor substrate according to the present invention; 
         FIGS. 9A and 9B  are a plane view and a sectional view describing a fourth mask process of the transflective thin film transistor substrate according to the present invention; 
         FIGS. 10A and 10B  are a plane view and a sectional view describing a fifth mask process of the transflective thin film transistor substrate according to the present invention; and 
         FIGS. 11A and 11D  are sectional views describing the fifth mask process of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. 
     Hereinafter, the preferred embodiment of the present invention will be described in detail with reference to  FIGS. 3 to 11D . 
       FIG. 3  is a plane view partially illustrating a transflective thin film transistor substrate according to an embodiment of the present invention, and  FIG. 4  is a sectional view illustrating the transflective thin film transistor substrate taken along lines II-II′, III-III, IV-IV′ of  FIG. 3 . 
     As shown in  FIGS. 3 and 4 , the transflective thin film transistor substrate includes a lower substrate  142 ; a gate line  102  and a data line  104  that define a pixel area on the lower substrate  142  crossing each other with a gate insulating film  144  therebetween; a thin film transistor  106  connected to the gate line  102  and the data line  104 ; a reflection electrode  152  formed at a reflection area of each pixel; and a pixel electrode  118  formed at each pixel area and connected to the thin film transistor  106  through the reflection electrode  152  and an upper storage electrode  122 . The transflective thin film transistor substrate includes a storage capacitor  120  formed by overlapping a storage line  150  with the upper storage electrode  122  connected to the pixel electrode  118  via the reflection electrode  152 ; a gate pad  124  connected to the gate line  102 ; and a data pad  134  connected to the data line  104 . The transflective thin film transistor substrate divides each pixel area into a reflection area where the reflection electrode  152  is formed and a transmission area where the reflection electrode  152  is not formed. 
     The thin film transistor  106  includes a gate electrode  108  connected to the gate line  102 ; a source electrode  110  connected to the data line  104 ; a drain electrode  112  facing the source electrode  110  to be connected to the pixel electrode  118 ; an active layer  114  overlapping the gate electrode  108  with a gate insulating film  144  therebetween to form a channel between the source electrode  110  and the drain electrodes  112 ; and an ohmic contact layer  116  formed on the active layer  114  except for a channel portion to make an ohmic contact with the source electrode  110  and the drain electrode  112 . The thin film transistor  106  responds to the scan signal of the gate line  102  to cause a video signal on the data line  104  to be charged and maintained in the pixel electrode  118 . A semiconductor pattern  115  including the active layer  114  and the ohmic contact layer  116  is formed to overlap the data line  104  as well. 
     The reflection electrode  152  is formed at the reflection area of each pixel to reflect an external light. The reflection electrode  152  has the embossing shape in accordance with the shape of the organic film  148 , thereby increasing its reflection efficiency due to its dispersion effect. Further, the reflection electrode  152  is connected via a transmission hole  150  penetrating the organic film  148  to a side surface of the upper storage electrode  122 . 
     The transmission hole  154  is formed at the transmission area to penetrate a gate insulating film  144 , the organic film  148 , the reflection electrode  152 , and the passivation film  146 . Accordingly, the length of the light path that runs through the liquid crystal layer becomes the same at the reflection area and the transmission area. Thus, the transmission efficiency of the reflection mode and the transmission mode becomes the same. As the transmission hole goes from the gate insulating film  144  to the passivation film  146 , its width becomes wider. Accordingly, the reflection electrode  152  formed at a reflection area is practically exposed. 
     The pixel electrode  118  independently formed at each pixel area overlapping with a partial portion of the reflection electrode  152  exposed through the transmission hole  154  and is connected. Accordingly, the pixel electrode  118  is connected to the reflection electrode  152  of the pixel electrode  118 , and to the drain electrode  112  of the thin film transistor  106  via the upper storage electrode  122  connected to the reflection electrode  152 . The pixel electrode  118  generates a potential difference with a common electrode of a color filter (not shown) by a pixel signal supplied through the thin film transistor. The potential difference causes liquid crystal molecules having dielectric anisotropy to rotate, thereby controlling the transmissivity of the light that runs through a liquid crystal layer in each of the reflection area and the transmission area. Thus, its brightness is changed in accordance with the video signal. Herein, an opening portion of the passivation film  146  overlaps with a partial transmission hole  154  and a partial reflection electrode  152  adjacent to the transmission hole  154 . Further, the passivation film  146  forms a boundary from the pixel electrode  118 . 
     The storage line  150  adjacent to the gate line  102  and crossing the data line  104  overlaps the upper storage electrode  122  connected to the pixel electrode  118  with the gate insulating film  144  therebetween, thereby forming the storage capacitor  120 . The upper storage electrode  122  is integrated with the drain electrode  112 , and is connected to the pixel electrode  118  through the reflection electrode  152 . The upper storage electrode  112  further overlaps the semiconductor pattern  115  under the upper storage electrode  122 . 
     The gate line  102  is connected to a gate driver (not shown) through the gate pad  124 . The gate pad  124  includes a lower gate pad electrode  128  extended from the gate line  102 ; and an upper gate pad electrode  130  connected to the lower gate pad electrode  128  via a contact hole  126  penetrating through the passivation film  146  and the gate insulating film  144 . 
     The data line  104  is connected to a data driver (not shown) through the data pad  134 . The data pad  134  includes a lower data pad electrode  138  extended from the data line  104 ; and an upper data pad electrode  130  connected to a side surface of the lower data pad electrode  138  via a second contact hole  136  penetrating the passivation film  146 , the lower data pad electrode  138 , and the semiconductor pattern  115 . 
     In the transflective thin film transistor substrate having the above structure, a transparent conductive pattern including the pixel electrode  118 , the upper gate pad electrode  130 , and the upper data pad electrode  140  is formed by the same patterning process of the transparent conductive layer. In this case, the transparent conductive layer is patterned by the lift-off process removing the photoresist pattern used in forming the transmission hole  154 , the first hole  126 , and the second contact hole  136 . The transmission hole  154 , the first hole  126 , and the second contact hole  136  penetrate from passivation film  146  to the gate insulating film  144  in the previous process. Accordingly, the transparent conductive pattern forms a boundary from an edge portion of the passivation film  146 . 
     As a result, the transflective thin film transistor substrate according to the embodiment of the present invention is formed by the following five mask processes.  FIGS. 5A and 5B  are a plane view and a sectional view explaining a first mask process in a fabricating method of the transflective thin film transistor substrate according to the embodiment of the present invention. 
     A gate pattern is formed by a first mask process where the gate pattern includes the gate line  102 , the gate electrode  108  connected to the gate line  102 , the lower gate pad electrode  128 , and the storage line  150  on the lower substrate  142 . More particularly, the gate metal layer is formed on the lower substrate by a deposition method such as sputtering. The gate metal layer is patterned by a photolithography process using a first mask and an etching process, thereby forming the gate pattern that includes the gate line  102 , the gate electrode  108 , the lower gate pad electrode  128 , and the storage line  150 . The gate metal layer is formed of a metal material such as Mo, Cu, Al(Nd), Cr, Ti, MoW, Ta or the like. Further, the gate metal layer can be formed with a double layer having a first conductive layer and a second conductive layer, wherein the first conductive layer is formed of ITO, TO, IZO or the like and the second conductive layer is formed of a metal material as mentioned above. 
       FIGS. 6A and 6B  are a plane view and a sectional view explaining a second mask process in a fabricating method of the transflective thin film transistor substrate according to the present invention.  FIGS. 7A to 7E  are sectional views specifically explaining the second mask process. 
     The gate insulating film  144  is formed on the lower substrate  142  where the gate pattern is formed. A source/drain pattern including the data line  104 , the source electrode  110 , the drain electrode  112 , the upper storage electrode  122  and the lower data pad electrode  138 , a semiconductor pattern  115  including the active layer  114  and the ohmic contact layer  116  that overlap along the rear surface of the source/drain pattern are formed on top thereof by a second mask process. The semiconductor pattern  115  and the source/drain pattern are formed by a one mask process using a diffractive exposure mask. 
     Specifically, the gate insulating film  144 , an amorphous silicon layer  105 , an amorphous silicon layer  107  doped with impurities n+ or p+, a source/drain metal layer  109  are sequentially formed on the lower substrate  142  where the gate pattern is formed as in  FIG. 7A . For example, the gate insulating film  144 , the amorphous silicon layer  105 , the amorphous silicon layer  107  doped with impurities are formed by PECVD, and the source/drain metal layer  109  is formed by sputtering. The gate insulating film  144  is formed of inorganic insulating material such as silicon oxide SiOx, silicon nitride SiNx and like. The source/drain metal layer  109  is formed of metal material such as Mo, Cu, Al(Nd), Cr, Ti, MoW, Ta or the like. 
     A photoresist  219  is spread over the source/drain metal layer  109 , and then the photoresist  219  is exposed and developed by a photolithography process using a diffractive exposure mask  210 , thereby forming a photoresist pattern  220  having the stepped difference as shown in  FIG. 7B . The diffractive exposure mask  210  includes a transparent quartz substrate  212 , a shielding layer  214  on top of the substrate  212  formed of a metal layer such as Cr and CrOx and the like, and a diffractive exposure slit  216 . The shielding layer  214  is located at an area where the semiconductor pattern and the source/drain pattern are to be formed to intercept ultraviolet ray, thereby leaving a first photoresist pattern  220 A after development. The diffractive exposure slit  216  is located at an area where the channel of the thin film transistor is to be formed to diffract the ultraviolet ray, thereby remaining a second photoresist pattern  220 B that is thinner than the first photoresist pattern  220 A after development. 
     Subsequently, the source/drain metal layer  109  is patterned by the etching process using the photoresist pattern  220  having a stepped difference, thereby forming the source/drain pattern and the semiconductor pattern  115  thereunder as shown in  FIG. 7C . In this case, the source electrode  110  and the drain electrode  112  in the source/drain pattern have a structure where they are integrated. 
     Then, the photoresist pattern  220  is ashed by an ashing process using an oxygen O 2  plasma. Thus, the first photoresist pattern  220 A becomes thinner and the second photoresist pattern  220 B is removed as shown in  FIG. 7D . The source/drain pattern exposed by the removal of the second photoresist pattern  220 B and the ohmic contact layer  116  thereunder are eliminated by the etching process using the ashed first photoresist pattern  220 A, thereby separating the source electrode  110  from the drain electrode  112  and exposing the active layer  114 . Accordingly, a channel of the active layer  114  is formed between the source electrode  110  and the drain electrode  112 . At this moment, both sides of the source/drain pattern are etched once more along the ashed first photoresist pattern  220 A, thus the source/drain pattern and the semiconductor pattern  115  have a fixed stepped difference in a step shape. 
     Then, the first photoresist pattern  220 A remaining on the source/drain pattern is removed by a strip process as in  FIG. 7E . 
       FIGS. 8A and 8B  are a plane view and a sectional view explaining a third mask process in a fabricating method of the transflective thin film transistor substrate according to the present invention. 
     On the gate insulating film  144  having the source/drain pattern formed by the third mask process, the transmission hole  154  is formed at the transmission area and the organic film  148  (having an embossing surface at the reflection area) removed at the pad area is formed. Specifically, the organic film  148  is formed on the gate insulating film  144  having the source/drain pattern by spin coating. The organic film  148  is formed of a photosensitive organic material such as acrylic resin. Then, the organic film  148  is patterned by the photolithography process using the third mask, that is, a half tone mask or a diffractive exposure mask. Thus the transmission hole  155  penetrating the organic film  148  is formed in the transmission area in correspondence to the transmission portion of the third mask, and the organic film  148  is removed at the pad area. Further, the remaining portion except for the transmission portion in the third mask has a structure that the shielding portion and the diffractive exposure portion (or transflective portion) are repeated. In correspondence thereto, the organic film  148  is patterned to have a structure where the shielding area (projected portion) and the diffractive exposure area (groove portion) having the stepped difference are repeated in the reflection area. Subsequently, the organic film  148  with the repeated projected portion and groove portion is cured to form the embossing shape on the surface of the organic film  148 . 
       FIGS. 9A and 9B  are a plane view and a sectional view explaining a fourth mask process in a fabricating method of the transflective thin film transistor substrate according to the present invention. 
     The reflection electrode  152  is formed at each pixel reflection area by the fourth mask process. Specifically, a reflective metal layer having an embossing surface is formed on the organic film  148  and maintains the embossing shape. The reflective metal layer is formed of a metal that has a high reflectivity like AlNd. Subsequently, the reflective metal layer is patterned by a photolithography process using the fourth mask and the etching process, thereby independently forming the reflection electrode  152  at every reflection area of each pixel. The reflection electrode  152  is connected to the drain electrode  112  via a side surface of the upper storage electrode  122  exposed at the edge portion of the transmission hole  154 . 
       FIGS. 10A and 10B  are a plane view and a sectional view explaining a fifth mask process in a fabricating method of the transflective thin film transistor substrate according to of the present invention,  FIGS. 11A and 11D  are sectional views to specifically describe the fifth mask process of the present invention. 
     In the fifth mask process, the transmission hole  154  penetrates from the passivation film  146  through the gate insulating film  144 ; the first and the second contact holes  126  and  136  exposing the lower gate pad electrode  128  and the lower data pad electrode  138  are formed; and a transparent conductive pattern including the pixel electrode  118 , the upper gate pad electrode  130  and the upper data pad electrode  140  is formed. 
     Specifically, as shown in  FIG. 11A , the passivation film  146  covering the reflection electrode  152  is formed by the deposition method such as PECVD. A photoresist pattern  230  is formed on the passivation film  146  by a photolithography process. The passivation film  146  is of an inorganic insulating material like that used for the gate insulating film  144 . The photoresist pattern  230  has an opened structure at the area having the transmission hole  154 , the lower gate pad electrode  128  and the lower data pad electrode  138 . 
     The passivation film  146  and the gate insulating film  144  are patterned by the etching process using the above photoresist pattern  230  so that the transmission hole  154  penetrates the passivation film  150  and the gate insulating film  144  as shown in  FIG. 11B , and the first and the second contact holes  126  and  136  exposing the lower gate pad electrode  128  and the lower data pad electrode  138  are formed. The transmission hole  154  exposes a partial reflection electrode  152 . The first contact hole  126  penetrates the passivation film  146  and the gate insulating film  144  to expose the lower gate pad electrode  128 . The second contact hole  136  penetrates the passivation film  146 , the lower data pad electrode  138  and the semiconductor pattern  115  to expose a side surface of the lower data pad electrode  138 . In this case, the edge part of the photoresist pattern  230  has more projected shape than the edge part of the passivation film  146  due to the over-etched passivation film  146 . The ashing process and the etching process are continually performed in the same chamber. 
     Subsequently, a transparent conductive film  117  is entirely on the thin film transistor substrate having the photoresist pattern  230  by a deposition method such as sputtering. The transparent conductive film  117  is formed of ITO, TO, IZO or the like. At this time, the transparent conductive film  117  deposited having a straight property by the edge portion of the projected photoresist pattern  230  is opened at the edge portion of the passivation film  146  to form a stripper osmosis path. 
     The photoresist pattern  230  and the transparent conductive film  117  on the photoresist pattern  230  are removed together by the lift-off process, thereby forming the transparent conductive pattern including the pixel electrode  118 , the upper gate pad electrode  132  and the upper data pad electrode  140 , as shown in  FIG. 11D . At this time, because the stripper is easily passed into the edge part of the passivation film  146  via the osmosis path formed by open of the transparent conductive film  117 , lift-off efficiency can be improved. The pixel electrode  118  forms a boundary from the passivation film  146  in the transmission hole  154 . The pixel electrode  118  is connected to the exposed reflection electrode  152 . The upper gate pad electrode  130  forms a boundary from the passivation film  146  in the first contact hole  126  to connected to the lower gate pad electrode  128 . The upper data pad electrode  140  forms a boundary from the passivation film  146  in the second contact hole  136  to connected to a side surface of the lower data pad electrode  138 . 
     As described above, in the transflective thin film transistor substrate and the method of driving the same, the transparent conductive pattern is formed by the lift-off process of the photoresist pattern used in forming the transmission hole and the contact hole that penetrate the passivation film and the gate insulating film, thereby simplifying the processes by performing a five mask process. 
     It will be apparent to those skilled in the art that various modifications and variations can be made in the liquid crystal display device and fabricating method thereof of 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.