Abstract:
A thin film transistor array substrate and a fabricating method are disclosed. A gate line and a data line cross each other and a thin film transistor (TFT) is provided at the intersection between the gate and data lines. A protective film covers the data line and the thin film transistor and has a contact hole exposing a drain electrode of the TFT. A pixel electrode is connected, via the contact hole, to the drain electrode of the TFT. A storage capacitor includes a gate insulating film between the pixel electrode and the gate line and/or a common line. Some or all of the protective film within the storage capacitor is removed such that the storage capacitor contains no protective film or a layer of protective film that is thinner than the portion covering the TFT.

Description:
RELATED APPLICATIONS  
       [0001]     This application claims the benefit of U.S. patent application Ser. No. 11/293,888, which claims priority to Japanese Patent Application No. 2004-101447, filed on Dec. 3, 2004, both of which are incorporated by reference. 
     
    
     TECHNICAL FIELD  
       [0002]     The present invention relates to a thin film transistor array substrate, and more particularly to a thin film transistor array substrate and a fabricating method thereof that are adaptive for minimizing a residual image to thereby improve picture quality.  
       DESCRIPTION OF THE RELATED ART  
       [0003]     Generally, a liquid crystal display (LCD) controls light transmittance of a liquid crystal using an electric field to thereby display a picture. To this end, the LCD includes a liquid crystal display panel having liquid crystal cells arranged in a matrix, and a driving circuit for driving the liquid crystal display panel. 2. Background Information  
         [0004]     The liquid crystal display panel includes a thin film transistor array substrate and a color filter array substrate opposed to each other, a liquid crystal injected between two substrates, and a spacer for keep a cell gap between two substrates.  
         [0005]     The color filter array substrate consists of color filters formed for each liquid crystal cell, black matrices for dividing the color filters and reflecting external light, common electrodes for commonly applying reference voltages to the liquid crystal cells, and an alignment film coated thereon.  
         [0006]     The liquid crystal display panel is completed by preparing the thin film array substrate and the color filter array substrate individually, joining them together, injecting liquid crystal between the joined substrates, and sealing the joined substrates.  
         [0007]      FIG. 1  is a plan view illustrating a related art thin film transistor array substrate, and  FIG. 2  is a section view of the thin film transistor array substrate taken along the I-I′ line in  FIG. 1 .  
         [0008]     Referring to  FIG. 1  and  FIG. 2 , the thin film transistor array substrate includes a gate line  2  and a data line  4  provided on a lower substrate  42  to intersect each other with the gate insulating film  44  therebetween, a thin film transistor  6  provided at each intersection, and a pixel electrode  18  provided at a cell area having a crossing structure. Further, the thin film transistor array substrate includes a storage capacitor  20  provided at an overlapped portion between the pixel electrode  18  and the pre-stage gate line  2 . The thin film transistor  6  includes a gate electrode  8  connected to the gate line  2 , a source electrode  10  connected to the data line  4 , a drain electrode  12  connected to the pixel electrode  18 , and an active layer  14  overlapping the gate electrode  8  and defining a channel between the source electrode  10  and the drain electrode  12 . The active layer  14  is provided to overlap with the data line  4 , the source electrode  10  and the drain electrode  12 , and further includes a channel portion between the source electrode  10  and the drain electrode  12 . On the active layer  14 , an ohmic contact layer  48  is deposited for making an ohmic contact with the data line  4 , the source electrode  10 , the drain electrode  12 .  
         [0009]     The thin film transistor  6  allows a pixel voltage signal applied to the data line  4  to be charged into the pixel electrode  18  and kept in response to a gate signal applied to the gate line  2 .  
         [0010]     The pixel electrode  18  is connected, via a first contact hole  16  passing through a protective film  50 , to the drain electrode  12  of the thin film transistor  6 . The pixel electrode  18  generates a potential difference with respect to a common electrode provided at an upper substrate (not shown) by the charged pixel voltage signal. This potential difference rotates a liquid crystal positioned between the thin film transistor array substrate and the upper substrate owing to dielectric anisotropy of the liquid crystal and transmits light inputted, via the pixel electrode  18 , from a light source (not shown) toward the upper substrate.  
         [0011]     The storage capacitor  20  is formed by a pre-stage gate line  2  and a pixel electrode  18 . The gate insulating film  44  and the protective film  50  are located between the gate line  2  and the pixel electrode  18 . The storage capacitor  20  allows a pixel voltage signal charged in the pixel electrode  18  to be stably maintained until the next pixel voltage is charged.  
         [0012]     Hereinafter, a method of fabricating the thin film transistor substrate will be described in detail with reference to  FIG. 3A  to  FIG. 3D .  
         [0013]     Firstly, a gate metal layer is formed on the lower substrate  42  by a deposition technique such as sputtering. Then, the gate metal layer is patterned by photolithography and etching using a first mask to thereby form gate metal patterns including the gate line  2 , the gate electrode  8  as shown  FIG. 3A .  
         [0014]     Next, the gate insulating film  44 , an amorphous silicon layer, a n+ amorphous silicon layer and a source/drain metal layer are sequentially provided on the lower substrate  42  provided with the gate metal patterns by deposition techniques such as plasma enhanced chemical vapor deposition (PECVD) and sputtering, etc.  
         [0015]     Then, a source/drain pattern including the data line  4 , the source electrode  10  and the drain electrode  12  is formed on the source/drain metal layer by photolithography and etching using a diffractive exposure mask; and a semiconductor pattern  45  including the active layer  14  and the ohmic contact layer  48  is formed at the lower portion of the source/drain pattern.  
         [0016]     Alternatively, the semiconductor pattern  45  may be provided individually with the source/drain pattern using a separate mask process.  
         [0017]     The protective film  50  is entirely formed on the gate insulating film  44  provided with the source/drain pattern by a deposition technique such as PECVD, etc. Thereafter, the protective film  50  is patterned by photolithography and etching to thereby provide a contact hole  16  as shown  FIG. 3C . The contact hole  16  passes through the protective film  50  and exposes the drain electrode  12 .  
         [0018]     A transparent electrode material is entirely deposited onto the protective film  50  by a deposition technique such as sputtering, etc. Thereafter, the transparent electrode material is patterned by photolithography and etching to thereby provide the pixel electrode  18  as shown  FIG. 3D . The pixel electrode  18  is electrically connected, via the first contact hole  16 , to the drain electrode  12 . Further, the pixel electrode  18  overlaps the pre-stage gate line  2  with the gate insulating film  44  and the protective film  50  therebetween, thereby providing the storage capacitor  20 .  
         [0019]     In the TFT array substrate, as shown in  FIG. 4 , the gate electrode  8  of the TFT  6  is supplied with a gate voltage (Vg) and the source electrode  10  thereof is supplied with a data voltage Vd. If a gate voltage more than a threshold voltage is applied to a gate voltage  8  of the TFT  6 , then a channel is formed between the source electrode  10  and the drain electrode  12 . In this case, the data voltage Vd is charged, via the source electrode  10  and the drain electrode  12  of the TFT  6 , into the liquid crystal cell Clc and the storage capacitor  20  Cst.  
         [0020]     Herein, a feed-through Voltage ΔVp, that is, a difference between the data voltage Vd and a voltage Vlc charged in the liquid crystal cell Clc is defined by the following equation:  
               Δ   ⁢           ⁢   Vp     =       Cgd     Cgd   +   Clc   +   Cst       ⁢   Δ   ⁢           ⁢   Vg             (   1   )             
 
 wherein Cgd is a parasitic capacitor formed between the gate terminal and the drain terminal of the TFT; and ΔVg is a difference voltage between a voltage Vgh and a voltage Vgl. 
 
         [0021]     Such a feed-through voltage ΔVp causes a deterioration of picture quality such as a residual image, for example, a flicker. Accordingly, studies have been undertaken for reducing the deterioration of picture quality by maximizing the capacitance Cst of the storage capacitor  120  in order to minimize the feed-through voltage ΔVp as indicated in the above equation (1). However, as the capacitance Cst of the storage capacitor  120  increases, an area occupied by the storage capacitor  120  increases commensurately. This reduces the aperture ratio of the pixel. Furthermore, if a thickness of the protective film  50  and the gate insulating film  44  is reduced, then the amount of insulation provided by the gate insulating film  44  and the protective film  50  decreases.  
       SUMMARY  
       [0022]     By way of introduction only, a thin film transistor array substrate according to one aspect of the present invention includes a gate line and a data line crossing each other; a thin film transistor provided at each intersection between the gate line and the data line; a storage capacitor including another gate line and/or a common line separated from the gate line; a protective film that covers the data line and the thin film transistor and the at least one of the other gate line or the common line in the storage capacitor, the protective film in the storage capacitor thinner than the protective film that covers the data line and the thin film transistor, the protective film having a contact hole exposing a drain electrode of the thin film transistor; and a pixel electrode connected, via the contact hole, to the drain electrode of the thin film transistor, the pixel electrode forming one electrode of the storage capacitor.  
         [0023]     A method of fabricating a thin film transistor array substrate according to another aspect of the present invention includes forming a gate line and a common line and/or another gate line separated from the gate line on a substrate; forming a data line crossing the gate line and a thin film transistor provided at the intersection between the gate line and the data line; forming a protective film covering the thin film transistor; removing a portion of the protective film to form a contact hole exposing a drain electrode of the thin film transistor and at least thin the protective film in a storage capacitor area; and forming a pixel electrode connected, via the contact hole, to the drain electrode of the thin film transistor, a storage capacitor being formed that includes the pixel electrode and at least one of the common line or the other gate line  
         [0024]     In another embodiment, a liquid crystal display includes a thin film transistor array substrate, a substrate that opposes the thin film transistor array substrate, and liquid crystal between the substrates. The thin film transistor array substrate includes: a first gate line and a data line crossing each other on a transparent substrate; a thin film transistor provided at an intersection of the first gate line and the data line; a protective film that covers the data line and the thin film transistor; a gate insulating film that covers the first gate line; and a pixel electrode connected to a drain electrode of the thin film transistor. The pixel electrode is separated from a conductive material by an insulator to form a storage capacitor in a storage capacitor area. The insulator includes the protective film and/or the gate insulating film. The thickness of the insulator in the storage capacitor area is thinner than a combined thickness of the protective film and the gate insulating film outside the storage capacitor area. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0025]     The following detailed description of the embodiments of the present invention reference the accompanying drawings in which:  
         [0026]      FIG. 1  is a plan view showing a portion of a related art thin film transistor array substrate;  
         [0027]      FIG. 2  is a section view of the thin film transistor array substrate taken along the I-I′ line in  FIG. 1 ;  
         [0028]      FIG. 3A  to  FIG. 3D  are section views illustrating a method of fabricating the thin film transistor substrate shown in  FIG. 2 ;  
         [0029]      FIG. 4  is a waveform diagram of a voltage applied to the liquid crystal panel;  
         [0030]      FIG. 5  is a section view showing a portion of a thin film transistor array substrate according to a first embodiment of the present invention;  
         [0031]      FIG. 6A  to  FIG. 7B  are section views illustrating a method of fabricating the thin film transistor substrate according to a first embodiment of the present invention;  
         [0032]      FIG. 8  is a section view showing a portion of a thin film transistor array substrate according to a second embodiment of the present invention;  
         [0033]      FIG. 9A  to  FIG. 9C  are section views illustrating a method of fabricating the thin film transistor substrate according to a second embodiment of the present invention; and  
         [0034]      FIG. 10  is a plan view showing a film transistor array substrate according to a third embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS  
       [0035]     Hereinafter, the preferred embodiments of the present invention will be described in detail with reference to  FIG. 5  to  FIG. 10 .  
         [0036]      FIG. 5  is a section view showing a thin film transistor array substrate according to a first embodiment of the present invention.  
         [0037]     Referring to  FIG. 5 , the thin film transistor array substrate includes a gate line  102  and a data line  104  provided on a lower substrate  142  to intersect each other with a gate insulating film  144  therebetween, a thin film transistor  106  provided at each intersection, and a pixel electrode  118  provided at a cell area having a crossing structure. Further, the thin film transistor array substrate includes a storage capacitor  120  provided at an overlapped portion between the pixel electrode  118  and the pre-stage gate line  102 . 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  connected to the pixel electrode  118 , and an active layer  114  overlapping the gate electrode  108  and defining a channel between the source electrode  110  and the drain electrode  112 . The active layer  114  overlaps the data line  104 , the source electrode  110  and the drain electrode  112  and has a channel portion between the source electrode  110  and the drain electrode  112 . On the active layer  114 , an ohmic contact layer  148  is deposited for making ohmic contact with the data line  104 , the source electrode  110 , and the drain electrode  112 .  
         [0038]     The thin film transistor  106  allows a pixel voltage signal applied to the data line  104  to be charged into the pixel electrode  118  and kept in response to a gate signal applied to the gate line  102 .  
         [0039]     The pixel electrode  118  is connected, via a first contact hole  116  passing through a protective film  150 , to the drain electrode  112  of the thin film transistor  106 . The pixel electrode  118  generates a potential difference with respect to a common electrode provided at an upper substrate (not shown) by the charged pixel voltage signal. This potential difference rotates a liquid crystal positioned between the thin film transistor array substrate and the upper substrate owing to dielectric anisotropy of the liquid crystal and transmits light inputted, via the pixel electrode  118 , from a light source (not shown) toward the upper substrate. The storage capacitor  120  is formed by the storage electrode  118  and the pre-stage gate line  102 . The gate insulating film  144  is located between the gate line  102  and the pixel electrode  118 .  
         [0040]     The protective film  150  is not located in the storage capacitor  120 . Thus, a feed-through voltage ΔVp is minimized. Accordingly, a residual image such as flicker is minimized to improve a picture quality.  
         [0041]     Hereinafter, this will be described in more detail  
         [0042]     Generally, a capacitance value of the capacitor is in proportion to a section area of the electrode while being in inverse proportion to a distance between the electrodes as indicated in the following equation: 
 
C˜A/d  (2) 
 
 wherein C represents a capacitance value of the capacitor; A represents an area of the capacitor; and d represents a distance between the electrodes of the capacitor. 
 
         [0043]     In the first embodiment of the present invention, the protective film  150  is not present on the gate insulating film  144  in the storage capacitor  120 . Accordingly, since a distance between the pixel electrode  118  and the gate electrode  102  is reduced, a capacitance value Cst of the storage capacitor  120  is increased. The capacitance Cst of the storage capacitor  120  plays a role to reduce a feed-through voltage ΔVp as indicated in the following equation:  
               Δ   ⁢           ⁢   Vp     =       Cgd     Cgd   +   Clc   +   Cst       ⁢   Δ   ⁢           ⁢   Vg             (   3   )             
 
         [0044]     As a result, the feed-through voltage ΔVp is minimized. Thus, a residual image problem such as flicker can be minimized to improve the picture quality.  
         [0045]     Hereinafter, a method of fabricating the thin film transistor substrate will be described in detail with reference to  FIG. 6A  to  FIG. 6D .  
         [0046]     Firstly, a gate metal layer is formed on the lower substrate  142  by a deposition technique such as sputtering. Then, the gate metal layer is patterned by photolithography and etching using a first mask to thereby provide gate metal patterns including the gate line  102 , the gate electrode  108  as shown  FIG. 6A . The gate metal layer may be a single-layer or multiple-layer structure of chrome (Cr), molybdenum (Mo) or an aluminum group metal, etc.  
         [0047]     The gate insulating film  144  is formed on the lower substrate  142  provided with the gate pattern by deposition techniques such as plasma enhanced chemical vapor deposition (PECVD) and sputtering, etc. The gate insulating film  144  is formed from an inorganic insulating material such as silicon oxide (SiOx) or silicon nitride (SiNx).  
         [0048]     An amorphous silicon layer, an n+ amorphous silicon layer and a source/drain metal layer are sequentially provided on the lower substrate  142  provided with the gate insulating film  142 .  
         [0049]     A photo-resist pattern is formed on the source/drain metal layer by photolithography using a mask. Herein, the mask has a diffractive exposure part at the channel portion of the thin film transistor  106 , thereby allowing the photo-resist pattern at the channel portion to have a lower height than at the source/drain regions.  
         [0050]     Subsequently, the source/drain metal layer is patterned by wet etching using the photo-resist pattern to thereby provide source/drain patterns including the data line  104 , the source electrode  110 , and the drain electrode  112 , which is integral with the source electrode  110 .  
         [0051]     Next, the amorphous silicon layer and the n+ amorphous silicon layer are simultaneously patterned by dry etching using the same photo-resist pattern to thereby provide the semiconductor pattern  145  including the ohmic contact layer  148  and the active layer  114 .  
         [0052]     Further, the photo-resist pattern having a relatively low height at the channel portion is removed by ashing, and thereafter the source/drain pattern and the ohmic contact layer  148  at the channel portion is etched by dry etching. Thus, the active layer  114  at the channel portion is exposed to disconnect the source electrode  110  from the drain electrode  112  as shown  FIG. 6B .  
         [0053]     Then, the photo-resist pattern left on the source/drain pattern group is removed by stripping. Herein, the source/drain metal is selected from molybdenum (Mo), titanium (Ti), tantalum (Ta) or a molybdenum alloy, Cu, an aluminum group metal etc.  
         [0054]     Alternatively, the semiconductor pattern  145  may be formed individually with the source/drain pattern using a separate mask process.  
         [0055]     The protective film  150  is entirely formed on the gate insulating film  144  provided with the source/drain patterns by a deposition technique such as PECVD, etc. The protective film  150  is patterned by photolithography and etching using a mask to thereby define a contact hole  116 . The contact hole  116  passes through the protective film  150  and exposes the drain electrode  112 . The gate insulating film  144  is exposed at an area provided with the storage capacitor.  
         [0056]     Hereinafter, a method of fabricating the protective film  150  will be described in detail with reference to  FIG. 7A  to  FIG. 7B .  
         [0057]     Referring to  FIG. 7A , after the protective film  150  is formed on the entire lower substrate  142 , a photo-resist  190   a  is entirely coated thereon. Then, after a mask  180  including a transmitting area  180   a  and a shielding area  180   b  is aligned, the photo-resist  190   a  under the transmitting area  180   a  is exposed to radiation.  
         [0058]     Next, as shown in  FIG. 7B , after a photo-resist pattern  190   b  is formed by development of the photo-resist  190   a , the protective film  150  is patterned by utilizing the photo-resist pattern as a mask. Thus, as shown in  FIG. 6C , a contact hole  116  is defined to expose the drain electrode  112  of the thin film transistor  106 . Also, the protective film  150  is removed at an area where the storage capacitor  120  is positioned, thereby exposing the gate insulating film  144 .  
         [0059]     The protective film  150  is made from an inorganic insulating material identical to the gate insulating film  144 , or an organic insulating material such as an acrylic organic compound having a small dielectric constant, BCB (benzocyclobutene) or PFCB (perfluorocyclobutane), etc.  
         [0060]     A transparent electrode material is entirely deposited onto the protective film  150  by a deposition technique such as sputtering, etc. Thereafter, the transparent electrode material is patterned by photolithography and etching using a fourth mask to thereby provide transparent electrode patterns including the pixel electrode  118 . The pixel electrode  118  is electrically connected, via a contact hole  116 , to the drain electrode  112 . Also, the storage capacitor  120  consists of a pixel electrode  118  overlapping a pre-stage gate line  102  with the gate insulating film  144  therebetween. The transparent electrode material is selected from indium-tin-oxide (ITO), tin-oxide (TO), indium-zinc-oxide (IZO) or the like.  
         [0061]     As described above, in the first embodiment of the present invention, the protective film  150  is removed from the storage capacitor  120  to thereby increase a capacitance of the storage capacitor  120 . Accordingly, a feed-through voltage ΔVp is minimized. Thus, a residual image problem such as flicker can be minimized to improve the picture quality.  
         [0062]      FIG. 8  is a section view showing a structure of a thin film transistor array substrate according to a second embodiment of the present invention.  
         [0063]     The thin film transistor substrate shown in  FIG. 8  has the same elements as the thin film transistor substrate shown in  FIG. 5  except that the protective film  150  is partially removed within the storage capacitor  120  to have a low height. Therefore, the same elements in  FIG. 8  are given the same reference numerals as those in  FIG. 5 . Further, an explanation as to the same elements will be omitted. The protective film  150  includes a contact hole  116  for exposing the drain electrode  112  of the thin film transistor  106 , and has a lower height than the prior art within the storage capacitor  120 .  
         [0064]     Accordingly, as a distance between the pixel electrode  118  and the gate electrode  102  is reduced, a capacitance value Cst of the storage capacitor  120  is increased. As a result, a feed-through voltage ΔVp is minimized. Thus, a residual image problem such as flicker can be minimized to improve the picture quality.  
         [0065]     According to the second embodiment of the present invention, the height of the protective film  150  within the storage capacitor  120  can be adjusted by forming the protective film  150  using a diffractive exposure mask. Thus, it becomes possible to increase a capacitance Cst of the storage capacitor  120 . Also, it becomes possible to provide the storage capacitor  120  having a desired capacitance value. Herein, the height of the protective film  150  in the storage capacitor  120  is controlled by controlling the etching time.  
         [0066]      FIG. 9A  to  FIG. 9C  are views for explaining a thin film transistor array substrate and a fabricating method thereof according to the second embodiment of the present invention.  
         [0067]     A method of fabricating the thin film transistor substrate according to the second embodiment of the present invention is identical to a method of fabricating the thin film transistor array substrate according to the first embodiment of the present invention as shown  FIG. 6A  to  FIG. 6D  except that the contact hole  116  for exposing the drain electrode  112  of the thin film transistor  106  is positioned and the partially removed protective film  150  is located within the storage capacitor  120  by forming the protective film  150  using a diffractive exposure mask. Therefore, an explanation as to the same elements will be omitted.  
         [0068]     Referring to  FIG. 9A , the protective film  150  and the photo-resist are sequentially provided on the lower substrate  142  provided with the thin film transistor etc. Thereafter, the photo-resist pattern  192   a  is provided by exposure and development after a diffractive exposure mask  182  including a transmitting part  182   a , a shielding part  182   b  and a semi-transmitting part  182   c  was aligned. Herein, the protective film  150  is exposed at an area where the contact hole  116  is to be defined, and has a relatively low height (A area in the drawing) at an area where the protective film  150  having a low thickness in the storage capacitor  120  is to be positioned.  
         [0069]     The protective film  150  is patterned by utilizing the photo-resist pattern  192   a  as a mask to thereby provide a contact hole  116  exposing a drain electrode  112  of the thin film transistor  106 . Next, ashing is carried out to expose the protective film  150  to be included in the storage capacitor  120  through the remaining photo-resist pattern  192   b  as shown in  FIG. 9B . Further, the exposed protective film  150  is etched (dry etched) by utilizing the remaining photo-resist pattern  192   b  as a mask to thereby leave the protective film  150  having a lower height than the protective film  150  at the area excluding the storage capacitor  129  as shown in  FIG. 9C . Herein, the thickness of the remaining protective film  150  is adjusted by adjusting the etching time. Thereafter, the remaining photo-resist pattern  192   b  is removed by stripping to thereby provide the partially removed protective film  150 .  
         [0070]      FIG. 10  is a plan view showing a film transistor array substrate according to a third embodiment of the present invention;  
         [0071]     The thin film transistor array substrate shown in  FIG. 10  is a thin film transistor array substrate of storage on common type in which the storage capacitor  120  is provided in such a manner to cross the pixel electrode  118 .  
         [0072]     Such a thin film transistor array substrate of storage on common type has the same elements as the thin film transistor array substrate shown in  FIG. 5  except that it crosses the pixel electrode  118  and is parallel with the gate line  102 . In addition, a common line  125  supplied with a reference voltage is provided upon driving the liquid crystal. The storage capacitor  120  is defined by the common line  125  and the pixel electrode  118 . Therefore, the same elements will be given by the same reference numerals, and a detailed explanation as to the same elements will be omitted. The thin film transistor array substrate according to the third embodiment of the present invention has a storage capacitor  120  that crosses a pixel area, that is, an area at which the pixel electrode is positioned.  
         [0073]     In the thin film transistor array substrate, the protective film  150  is completely or partially removed within the storage capacitor  120  to have a low height like the first and second embodiments of the present invention. In the third embodiment, the storage capacitor  120  is defined by the common line  125  and the pixel electrode  118  rather than the gate line  102 .  
         [0074]     As described above, the storage-on-common type thin film transistor array substrate according to the third embodiment of the present invention is formed such that the protective film is completely or partially removed within the storage capacitor. Accordingly, a distance between the pixel electrode  118  and the gate electrode  102  is reduced to increase a capacitance Cst of the storage capacitor  120 . As a result, a feed-through voltage ΔVp is minimized. Thus, a residual image problem such as flicker can be minimized to improve the picture quality.  
         [0075]     Herein, when the protective film  150  is partially removed within the storage capacitor  120 , the diffractive mask  182  is used. Accordingly, it becomes possible to increase a capacitance Cst of the storage capacitor  120 . Also, it becomes possible to provide a storage capacitor  120  having a desired capacitance value.  
         [0076]     In the method of fabricating the thin film transistor substrate according to the third embodiment of the present invention, a gate pattern such as the gate line  102  is formed simultaneously with the common line  125 . When the protective film is completely removed from the storage capacitor  120 , the same method as shown in  FIG. 7A  to  FIG. 7B  is used. On the other hand, when the protective film  150  is partially removed from the storage capacitor  120 , the gate line  102  and the common line  125  are formed by the same method as the patterning process including photolithographic, ashing, etching processes, etc employing the diffractive exposure mask  182  shown  FIG. 9A  to  FIG. 9C . Accordingly, the detailed description as to this will be omitted.  
         [0077]     As described above, according to the present invention, the protective film within the storage capacitor is completely or partially removed, thereby increasing a capacitance of the storage capacitor. Accordingly, a feed-through voltage ΔVp is minimized. Thus, a residual image problem such as flicker can be minimized to improve the picture quality.  
         [0078]     Although the present invention has been explained by the embodiments shown in the drawings described above, it should be understood to the ordinary skilled person in the art that the invention is not limited to the embodiments, but rather that various changes or modifications thereof are possible without departing from the spirit of the invention. Accordingly, the scope of the invention shall be determined only by the appended claims and their equivalents.