Abstract:
A TFT matrix-type liquid crystal display device is used in laptop personal computers and wall TVs. On a transparent insulating substrate  10  there are formed gate bus lines  14  for commonly connecting the gates of thin film transistors, drain bus lines  16  for commonly connecting the drains of the thin film transistors, and outside terminals  20  and outside terminals  30  opposed respectively to the ends of the gate bus lines and the drain bus lines  16 . Gate connection lines  24  for commonly connecting the gate bus lines  14  and drain connection lines  34  for commonly connecting the drain bus lines are formed in regions inner of the outside terminals  20, 30.  The thin film transistor matrix device can be fabricated without occurrence of short circuit defects, with little characteristic change and with high yields.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     The present invention relates to a thin film transistor matrix device and a method for fabricating the same, more specifically a TFT-LCD (TFT matrix-type liquid crystal display device) for use in laptop personal computers and wall TVs, and a method for fabricating the same.  
         [0002]     TFT-LCDs have characteristics of thinness and lightness, low electric power consumption, etc. and are expected to have a large market in the future as a display device which will take place of CRTs. To realize TFT panels of high precision, large screens for use in work stations, etc., the aperture ratio is a significant problem for higher image quality. To fabricate inexpensive TFT panels, it is important that the TFT panels have device structures which can be fabricated by the use of photolithography techniques.  
         [0003]     A pattern layout of a conventional thin film transistor matrix device is shown in  FIG. 35 .  
         [0004]     An image d-splay region  112  is disposed at the center of a transparent insulating substrate  110 , and a plurality of thin film transistors (not shown) and a plurality of picture element electrodes (not shown) connected to the sources of the respective thin film transistors are arranged in a matrix in the region. The gate electrodes of the thin film transistors are commonly connected to gate bus lines  114   a  and  114   b  arranged widthwise as viewed in  FIG. 35 , and the drain electrodes thereof are commonly connected to drain bus lines  116   a  and  116   b  arranged lengthwise as viewed in  FIG. 35 .  
         [0005]     The plural gate bus lines  114   a  and  114   b  are separated in odd number-th gate bus lines  114   a  which are adjacent to each other, and even number-th gate bus lines  114   b  (in this specification, the term “odd number-th lines” is used to refer to the odd numbered lines, namely the first, third, fifth, . . . lines; the term “even number-th lines” is used to refer to the even numbered lines, namely the second, fourth, sixth, . . . lines). The odd number-th gate bus lines  114   a  are connected to gate side tab terminals  118   a  on the right side as viewed in  FIG. 35 , and the even number-th gate bus lines  114   b  are connected to gate side tab terminals  118   b  on the left side as viewed in  FIG. 35 .  
         [0006]     The plural drain bus lines  116  are separated in odd number-th drain bus lines  116   a  which are adjacent to each other, and even number-th drain bus lines  116   b . The odd number-th drain bus lines  116   a  are connected to drain side tab terminals  120   a  on the upper side as viewed in  FIG. 35 , and the even number-th drain bus lines  116   b  are connected to drain side tab terminals  120   b  on the lower side as viewed in  FIG. 35 .  
         [0007]     In the thus-structured thin film transistor matrix device, as described above, the gate bus lines  114   a ,  114   b , and the drain bus lines  116   a ,  116   b  are respectively formed by independent conducting layer patterns. As a result problems due to electric stresses, such as electrostatic charges, etc., occur in the process for fabricating the thin film transistor and in the process for fabricating the liquid crystal panel, whereby the conducting layer patterns are short-circuited and the characteristics of the thin film transistors, such as threshold values, etc., are changed.  
       SUMMARY OF THE INVENTION  
       [0008]     An object of the present invention is to provide a thin film transistor matrix device and a method for fabricating the same, which is free from occurrence of short-circuit and characteristic changes due to stresses, such as electrostatic charges, etc. and which can be fabricated with high yields.  
         [0009]     Another object of the present invention is to provide a thin film transistor matrix device and a method for fabricating the same, which can be inspected with high precision, so that possible defective products can be rejected beforehand.  
         [0010]     The above-described objects are achieved by a thin film transistor matrix device comprising: transparent insulating substrate; a plurality of thin film transistors arranged on the transparent insulating substrate in a matrix; a plurality of picture element electrodes arranged on the transparent insulating substrate in a matrix and connected to the sources of the thin film transistors; a plurality of bus lines for commonly connecting the gates or the drains of the thin film transistors; outside terminals formed on a margin of the transparent insulating substrate and opposed to the ends of the bus lines; and connection lines formed in regions inner of the outside terminals and commonly connecting said plurality of bus lines, whereby even when electric stresses due to electrostatic charges are applied in the process for fabricating the thin film transistor matrix device, the device can be fabricated without short-circuit defects and with little characteristic change and high yields.  
         [0011]     In the above-described thin film transistor matrix device it is preferable that the connection lines include a plurality of connection lines, said plurality of gate bus lines which are adjacent to each other being respectively commonly connected to said plurality of connection lines, whereby inspection of high precision is possible by applying different voltages to the connection lines, so that defective products can be expelled beforehand.  
         [0012]     It is preferable that the above-described thin film transistor matrix device further comprises resistant lines which interconnect said plurality of connection lines and have a higher resistant value than the connection lines.  
         [0013]     The above-described objects are achieved by a transparent insulating substrate; a plurality of thin film transistors arranged on the transparent insulating substrate in a matrix; a plurality of picture element electrodes arranged on the transparent insulating substrate in a matrix and connected to the sources of the thin film transistors; a plurality of gate bus lines for commonly connecting the gates of the thin film transistors; a plurality of drain bus lines for commonly connecting the drains of the thin film transistors; first outside terminals formed on a margin of the transparent insulating substrate and opposed to the ends of the gate bus lines; second outside terminals formed on a margin of the transparent insulating substrate and opposed to the ends of the drain bus lines; and gate connection lines formed in an inner region of the second outside terminals and commonly connecting said plurality of drain bus lines, whereby even when electric stresses due to electrostatic charges are applied in the process for fabricating the thin film transistor matrix device, the device can be fabricated without short-circuit defects and with little characteristic change and high yields.  
         [0014]     In the above-described thin film transistor matrix device it is preferable that the thin film transistor matrix device further comprises resistant lines for interconnecting the gate connection lines and the drain connection lines, and having a higher resistant value than the gate connection lines and the drain connection lines.  
         [0015]     In the above-described thin film transistor matrix device it is preferable that a first gate connection line and a second gate connection line respectively commonly connect said plurality of gate bus lines which are adjacent to each other, and a first drain connection line and a second drain connection line respectively commonly connect said a plurality of gate drain lines which are adjacent to each other.  
         [0016]     In the above-described thin film transistor matrix device it is preferable that the thin film transistor matrix device further comprises resistant lines for interconnecting the first and the second gate connection lines, and the first and the second drain connection lines and having a resistant value than said plurality of connection lines, whereby inspection of high precision is possible by applying different voltages to the connection lines, so that defective products can be rejected beforehand  
         [0017]     The above-described objects are achieved by the method for fabricating a thin film transistor matrix device comprising: a first step of forming on a transparent insulating substrate a plurality of gate bus lines for commonly connecting the gates of thin film transistors, first outside terminals opposed to ends of the gate bus lines, and a gate connection line formed in a region inner of the first outside terminals for commonly connecting said plurality of gate bus lines; a second step of forming a first insulating film on the entire surface; and a third step of forming on the first insulating film a plurality of drain bus lines for commonly connecting the drains of the thin film transistors, second outside terminals opposed to the ends of the drain bus lines, and a drain connection line formed in a region inner of the second outside terminals for commonly connecting said plurality of drain bus lines.  
         [0018]     The above-described objects are achieved by the method for fabricating a thin film transistor matrix device comprising: a first step of forming on a transparent insulating substrate a plurality of gate bus lines for commonly connecting the gates of thin film transistors, first outside terminals opposed to the ends of the gate bus lines, and a first gate connection line for commonly connecting the gate bus lines of one of groups in which adjacent ones of said plurality of gate bus lines are divided; a second step of forming a first insulating film on the entire surface; a third step of forming on the first insulating film a plurality of drain bus lines for commonly connecting the drains of the thin film transistors, second outside terminals opposed to the ends of the drain bus lines, and a first drain connection line for commonly connecting the drain bus lines of one of groups in which adjacent ones of said plurality of drain bus lines are divided; a fourth step of forming a second insulating film on the entire surface; and a fifth step of forming on the second insulating film picture element electrodes, a second gate connection line for commonly connecting the gate bus lines of the other of the groups in which adjacent ones of said plurality of gate bus lines are divided, and a second drain connection line for commonly connecting the drain bus lines of the other of the groups in which adjacent ones of said plurality of drain bus lines are divided.  
         [0019]     The above-described objects are achieved by the method for fabricating a thin film transistor matrix device comprising: a first step of forming on a transparent insulating substrate a plurality of gate bus lines for commonly connecting the gates of thin film transistors, first outside terminals opposed to the ends of the gate bus lines, a fist gate connection line for commonly connecting the gate bus lines of one of groups in which adjacent ones of said plurality of gate bus lines are divided, and a first drain connection line for commonly connecting the drain bus lines of one of groups in which adjacent ones of said plurality of drain bus lines are divided; a second step of forming a first insulating film on the entire surface; and a third step forming on the first insulating film said plurality of drain bus lines for commonly connecting the drains of the thin film transistors, second outside terminals opposed to the ends of the drain bus lines; a second drain connection line for commonly connecting the drain bus lines of the other of the groups in which adjacent ones of said plurality of drain bus lines are divided, and a second gate connection line for commonly connecting the gate bus lines of the other of the groups in which adjacent ones of said plurality of gate bus lines are divided.  
         [0020]     The above-described objects are achieved by the method for fabricating a thin film transistor matrix device comprising: a first step of forming on a transparent insulating substrate a plurality of gate bus lines for commonly connecting the gates of thin film transistors, first outside terminals opposed to the ends of the gate bus lines, a first gate connection line for commonly connecting the gate bus lines of one of groups in which adjacent ones of said plurality of gate bus lines are divided, and a first drain connection line for commonly connecting the drain bus lines of one of groups in which adjacent ones of said plurality of drain bus lines are divided; a second step of forming a first insulating film on the entire surface; a third step of forming on the first insulating film said plurality of drain bus lines for commonly connecting the drains of the thin film transistors, second outside terminals opposed to the ends of the drain bus lines, a second drain connection line, and a second gate connection line; a fourth step of forming a second insulating film on the entire surface; and a fifth step of forming on the second insulating film picture element electrodes, a first connection line for connecting the drain bus lines of the other of the groups in which adjacent ones of said plurality of drain lines are divided to the second drain connection line, and a second connection line for connecting the gate bus lines of the other of the groups in which adjacent ones of said plurality of gate bus lines are divided to the second gate connection line.  
         [0021]     In the above-described method for fabricating a thin film transistor matrix device, it is preferable that the method further comprises a fourth step of forming a second insulating film on the entire surface after the third step; and a fifth step of forming on the second insulating film picture element electrodes, and a resistant line for interconnecting the gate connection lines and the drain connection lines.  
         [0022]     In the above-described method for fabricating a thin film transistor matrix device, it is preferable that in the fifth step resistant lines for interconnecting the first and the second gate connection lines and the first and the second drain connection lines are formed.  
         [0023]     In the above-described method for fabricating a thin film transistor matrix device, it is preferable that after the fabrication steps are over, the gate bus lines are electrically disconnected from the gate connection lines, and the drain bus lines are electrically disconnected from the drain connection lines. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0024]      FIG. 1  is a plan view of the thin film transistor matrix device according to a first embodiment of the present invention.  
         [0025]      FIG. 2  is an enlarged plan view of the thin film transistor matrix device of  FIG. 1 .  
         [0026]      FIG. 3  is an enlarged plan view of an image display region of the thin film transistor matrix device of  FIG. 1 .  
         [0027]      FIG. 4  is a sectional view of the thin film transistor matrix device of  FIGS. 2 and 3 .  
         [0028]      FIGS. 5A  to  5 D are sectional views of the thin film transistor matrix device according to the first embodiment of the present invention at the respective steps of a method for fabricating the same (Part  1 ).  
         [0029]      FIGS. 6A  to  6 D are sectional views of the thin film transistor matrix device according to the first embodiment of the present invention at the respective steps of a method for fabricating the same (Part  2 ).  
         [0030]      FIG. 7  is a plan view of the thin film transistor matrix device according to a second embodiment of the present invention.  
         [0031]      FIG. 8  is an enlarged plan view of the thin film transistor matrix device of  FIG. 7 .  
         [0032]      FIG. 9  is a plan view of the thin film transistor matrix device according to a third embodiment of the present invention.  
         [0033]      FIG. 10  is an enlarged plan view of the thin film transistor matrix device of  FIG. 9 .  
         [0034]      FIG. 11  is sectional views of the thin film transistor matrix device of  FIG. 10 .  
         [0035]      FIGS. 12A  to  12 D are sectional views of the thin film transistor matrix device according to the third embodiment of the present invention at the respective steps of a first method for fabricating the same (Part  1 ).  
         [0036]      FIGS. 13A  to  13 D are sectional views of the thin film transistor matrix device according to the third embodiment of the present invention at the respective steps of the first method for fabricating the same (Part  2 ).  
         [0037]      FIG. 14  is a plan view of the thin film transistor matrix device according to the third embodiment of the present invention at the respective steps of the first method for fabricating the same (Part  1 ).  
         [0038]      FIG. 15  is a plan view of the thin film transistor matrix device according to the third embodiment of the present invention at the respective steps of the first method for fabricating the same (Part  2 ).  
         [0039]      FIG. 16  is a plan view of the thin film transistor matrix device according to the third embodiment of the present invention at the respective steps of the first method for fabricating the same (Part  3 ).  
         [0040]      FIG. 17  is a plan view of the thin film transistor matrix device according to the third embodiment of the present invention at the respective steps of the first method for fabricating the same (Part  4 ).  
         [0041]      FIGS. 18A  to  18 D are sectional views of the thin film transistor matrix device according to the third embodiment of the present invention at the respective steps of a second method for fabricating the same (Part  1 ).  
         [0042]      FIGS. 19A  to  19 C are sectional views of the thin film transistor matrix device according to the third embodiment of the present invention at the respective steps of the second method for fabricating the same (Part  2 ).  
         [0043]      FIG. 20  is a plan view of the thin film transistor matrix device according to the third embodiment of the present invention at a step of the second method for fabricating the same (Part  1 ).  
         [0044]      FIG. 21  is a plan view of the thin film transistor matrix device according to the third embodiment of the present invention at a step of the second method for fabricating the same (Part  2 ).  
         [0045]      FIG. 22  is a plan view of the thin film transistor matrix device according to the third embodiment of the present invention at a step of the second method for fabricating the same (Part  3 ).  
         [0046]      FIG. 23  is a plan view of the thin film transistor matrix device according to the third embodiment of the present invention at a step of the second method for fabricating the same (Part  4 ).  
         [0047]      FIG. 24  is a plan view of the thin film transistor matrix device according to a fourth embodiment of the present invention.  
         [0048]      FIG. 25  is an enlarged plan view of the thin film transistor matrix device of  FIG. 24 .  
         [0049]      FIG. 26  is sectional views of the thin film transistor matrix device of  FIG. 25 .  
         [0050]      FIGS. 27A  to  27 D are sectional views of the thin film transistor matrix device according to the fourth embodiment of the present invention at the respective steps of a first method for fabricating the same (Part  1 ).  
         [0051]      FIGS. 28A  to  28 D are sectional views of the thin film transistor matrix device according to the fourth embodiment of the present invention at the respective steps of the first method for fabricating the same (Part  2 ).  
         [0052]      FIG. 29  is a plan view of the thin film transistor matrix device according to the fourth embodiment of the present invention at a step of the first method for fabricating the same (Part  1 ).  
         [0053]      FIG. 30  is a plan view of the thin film transistor matrix device according to the fourth embodiment of the present invention at a step of the first method for fabricating the same (Part  2 ).  
         [0054]      FIG. 31  is a plan view of the thin film transistor matrix device according to the fourth embodiment of the present invention at a step of the fourth method for fabricating the same (Part  3 ).  
         [0055]      FIG. 32  is a plan view of the thin film transistor matrix device according to the fourth embodiment of the present invention at a step of the fourth method for fabricating the same (Part  4 ).  
         [0056]      FIG. 33  is a plan view of the thin film transistor matrix device according to a fifth embodiment of the present invention.  
         [0057]      FIG. 34  is an enlarged plan view of the thin film matrix device of  FIG. 33 .  
         [0058]      FIG. 35  is a plan view of a conventional thin film matrix device. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
     1. A First Embodiment  
       [0000]     1.1 Thin film Transistor Matrix Device  
         [0059]     The thin film transistor matrix device according to a first embodiment of the present invention will be explained with reference to FIGS.  1  to  6 .  
         [0060]      FIG. 1  shows a pattern layout of the thin film transistor matrix device according to the present embodiment.  FIG. 2  is an enlarged view of a wiring region of the thin film transistor matrix device.  FIG. 3  is an enlarged view of an image display region of the thin film transistor matrix device of  FIG. 1 .  FIG. 4  is a sectional view of the thin film transistor matrix device of  FIG. 1 .  
         [0061]     First, with reference to  FIG. 1 , the general layout of the thin film transistor matrix device according to the present embodiment will be explained.  
         [0062]     In the thin film transistor matrix device according to the present embodiment, a gate drive circuit and a drain drive circuit are mounted only on one side of a transparent insulating substrate  10 .  
         [0063]     An image display region  12  is provided at the center of the transparent insulating substrate  10 , and a plurality of thin film transistors (not shown) and a plurality of image electrodes (not shown) connected to the sources of the thin film transistors are arranged in a matrix in the region  12 . The gate electrodes of the plural thin film transistors are commonly connected to the gate bus lines  14  which are arranged widthwise as viewed in  FIG. 1 , and the drain electrodes of the plural thin film transistors are commonly connected to drain bus lines  16  which are arranged lengthwise as viewed in  FIG. 1 .  
         [0064]     The gate bus lines  14  are extended to the left as viewed in  FIG. 1  and have bumps  18  formed on the ends thereof. On a margin of the transparent insulating substrate  10  there are formed input terminals  20  which receives signals from the outside. The inner ends of the input terminals  20  and the bumps  18  of the gate bus lines  14  are opposed to each other in IC chip regions  22  where driver IC chips (not shown) are disposed.  
         [0065]     A gate connection line  24  which commonly connects with the gate bus lines  14  is longitudinally in the IC chip region  22  between the input terminals  20  and the bumps  18 . The gate connection line  24  and the bumps  18  of the gate bus lines  14  are connected with each other by thin connection lines  26 . The thin connection lines  26  are finally melted off by laser beams to electrically disconnect the gate bus lines  14  from the gate connection line  24 .  
         [0066]     The drain bus lines  16  are extended upward as viewed in  FIG. 1 , and bumps  28  are formed on the ends of the drain bus lines  16 . Input terminals  30  which receive signals from the outside are formed on a margin of the transparent insulating substrate  10 . The inner ends of the input terminals  30  and the bumps  28  of the drain bus lines  16  are opposed to each other in an IC chip region  32  where driver IC chips (not shown) are mounted.  
         [0067]     A drain connection line  34  which commonly connects the drain bus lines is extended widthwise as viewed in  FIG. 1  in the IC chip region  32  between the input terminals  30  and the bumps  28 . Thin connection lines  36  interconnect the drain connection line  34  and the bumps  28  of the drain bus lines  16 . The thin connection lines  36  are finally melted off by laser beams to electrically disconnect the drain bus lines  14  from the drain connection line  34 .  
         [0068]     The gate connection line  24  and the drain connection line  34  are connected with each other by a resistant wire  38  having a higher resistance value than the gate connection line  24  and the drain connection line  34 .  
         [0069]     Next, the thin film transistor matrix device according to the present embodiment will be detailed with reference to FIGS.  2  to  4 . In  FIG. 4 , the drawing on the left is a sectional view of the bumps  28  of the drain bus lines  16  along the line A-A′ in  FIG. 2 , the drawing on the right is a sectional view of the bumps  18  of the gate bus lines  14  along the line B-B′ in  FIG. 2 , and the drawing at the center is a sectional view of the thin film transistors and the picture element electrodes along the line C-C′ in  FIG. 3 .  
         [0070]     The image display unit  12  of the thin film transistor matrix device will be detailed with reference to the plan view of the image display region of  FIG. 3  and the line C-C′ sectional view in  FIG. 4 .  
         [0071]      FIG. 3  shows a plane structure of the image display unit  12 . The thin film transistors  40  are disposed at the intersections between the gate bus lines  14  and the drain bus lines  16 . The thin film transistors  40  have the gate electrodes  40   g  connected to the gate bus lines  14 , the drain electrodes  40   d  connected to the drain bus lines  16  and the source electrodes  40   s  connected to the picture element electrodes  42 . Capacitors  44  are disposed at the centers of the picture element electrodes  42 .  
         [0072]     A sectional structure of the image display unit  12  is shown by the C-C′ sectional view in  FIG. 4 . On the transparent insulating substrate  10  there are formed the gate bus lines  14  of a metal layer  46  of, e.g., Al or Cr, and capacitor electrodes  46   a  of the capacitors  44 . The gate bus lines  14  and the capacitor electrodes  46   a  share the same layer with the gate electrodes  40   g.    
         [0073]     On the metal layer  46  there is formed a first insulating film  48  of an SiN film, a two-layer film of an SiO 2  film and an SiN film, or others. The first insulating film  48  shares the same layer with a gate insulating film of the thin film transistors  40 .  
         [0074]     On the first insulating film  48  there is formed a semiconductor active layer  50  of, e.g., i-type a-Si. The semiconductor active layer  50  shares the same layer with a channel layer of the thin film transistors  40 . On the semiconductor active layer  50  there are formed the source electrodes  40   s  of the metal layer  52  of, e.g., Al, Cl or others, and counter electrodes  52   a  of the capacitors  44 .  
         [0075]     A second insulating film  54  of, e.g., an SiN film, a two-layer film of an SiO 2  film and an SiN film, or others, is formed on the metal layer  52 . In the second insulating film  54 , contact holes are formed on the source electrodes  40   s  and the counter electrodes  52   a.    
         [0076]     An transparent electrode film  56  of, e.g., ITO or others, is formed on the second insulating film  54 . The transparent electrode film  56  forms the picture element electrodes  42  and is connected to the source electrodes  40   s  and the counter electrodes  52   a  through the contact holes.  
         [0077]     The bumps  28  of the drain bus lines  16  of the thin film transistor matrix device will be detailed with reference to the plan view of  FIG. 2  and the A-A′ sectional view in  FIG. 4 .  
         [0078]     The first insulating film  48  is formed on the transparent insulating substrate  10 . The semiconductor active layer  50  and the metal layer  52  are laid on the first insulating film  48 . The second insulating film  53  is formed on the metal layer  52 . Contact holes are formed in the second insulating film  54  on the metal layer  52 . The transparent electrode film  56  is formed on the second insulating film  54 . The transparent electrode film  56  is connected to the metal layer  52  through the contact holes. The bumps  28  are constituted by the transparent electrode film  56  and the metal layer  52 . The drain connection line  34  commonly connecting the drain bus lines  16 , and the thin connection lines  26  share the metal layer  52  with the bumps  28 .  
         [0079]     The bumps  18  of the gate bus lines  14  of the thin film transistor matrix device will be explained with reference to the plan view of  FIG. 2  and the B-B′ sectional view in  FIG. 4 .  
         [0080]     The metal layer  46  is formed on the transparent insulating film  10 . The first insulating film  48  and the second insulating film  54  are formed on the metal layer  46 . Contact holes are formed in the first and the second insulating films  48 ,  54  on the metal layer  46 . The transparent electrode film  56  is formed on the second insulating film  54 . The transparent electrode film  56  is connected to the metal layer  46  through the contact holes. The transparent electrode film  56  and the metal layer  46  constitute the bumps  18 . The bumps  18  may be constituted by one of the transparent electrode film  56  and the metal layer  46 . The gate connection line  24  commonly connecting the gate bus lines  14 , and the thin connection lines  26  share the metal layer  46  with the bumps  18 .  
         [0081]     A liquid crystal panel is constituted by the above-described thin film transistor matrix device. An opposed substrate (not shown) having a color filter formed thereon is prepared, and a liquid crystal is sandwiched between the thin film transistor matrix device and the opposed substrate, and the liquid crystal panel is prepared.  
         [0082]     A circuit substrate (not shown) for the liquid crystal panel, which includes peripheral circuits, such as a drive circuit, is prepared. The liquid crystal panel and the circuit substrate are connected by a connection line (not shown), such as a flexible cable or others, and a liquid crystal display unit is prepared.  
         [0000]     1.2 Method for Fabricating the Thin Film Transistor Matrix Device  
         [0083]     Then, the method for fabricating the thin film transistor matrix device according to the present embodiment will be explained with reference to  FIGS. 5 and 6 . In the this method five masks are used.  
         [0084]     First, the metal layer  46  of, e.g., Al, Cr or others is formed by sputtering on a transparent insulating substrate  19 , such as a glass substrate or others. The metal layer  46  is patterned by the use of a first mask to form the gate bus lines  14 , the gate electrodes  42   a , the capacitor electrodes  46   a , the metal layer  46  of the bumps  18 , the gate connection line  24  and the thin connection lines  26  ( FIG. 5A ).  
         [0085]     Then, the first insulating film  48  of an SiN film, a two-layer film of SiO 2  film and SiN film, or others is formed by plasma CVD.  
         [0086]     Next, the semiconductor active layer  50  of non-doped i-type a-Si and a protection film (not shown) of an SiO2 film or an SiN film are continuously formed on the first insulating film  48  by plasma CVD ( FIG. 5B ). Subsequently all the protection film is etched off except a part thereof on the TFT channel region with a hydrofluoric acid buffer solution or others and by the use of a second mask.  
         [0087]     Then, an n + -type a-Si layer (not shown) is formed on the entire surface by plasma CVD.  
         [0088]     Then, the metal layer  52  of Al, Cr, or others is formed on the n + -type a-Si layer by sputtering ( FIG. 5C ).  
         [0089]     Then, by the use of a third mask, the metal layer  52  and the semiconductor active layer  50  are patterned to form the metal layers  52  of the bumps  28 , the source electrodes  40   s , the counter electrodes  52   a , the drain electrodes  40   d , drain bus lines  16 , the drain connection line  34  and the thin connection lines  26  ( FIG. 5D ).  
         [0090]     Next, the second insulation film  54  of an SiN film, a two-layer film of an SiO 2  film and an SiN film, or others is formed on the entire surface by plasma CVD ( FIG. 6A ).  
         [0091]     Next, by the use of a fourth mask, the second insulation film  54  and the first insulation film  48  are patterned to form the contact holes for the bumps  28 , the contact holes for the source electrodes  40   s , the contact holes for the counter electrodes  52   a , the contact holes for the bumps  18  and the contact hole for the resistant line  38  ( FIG. 6B ). Then, the transparent electrode film  56  is formed on the entire surface by sputtering ( FIG. 6C ).  
         [0092]     Next, by the use of a fifth mask, the transparent electrode film  56  is patterned to form the bumps  28 , the picture element electrodes  42 , the resistant line  38  ( FIG. 6D ). The resistant line  38  is so patterned that the end of the gate connection line and the end of the drain connection line  34  are connected with each other.  
         [0093]     Thus, by the use of  5  masks, the thin film transistor matrix device is fabricated.  
         [0094]     According to the present embodiment, the gate bus lines  14  are commonly connected to the gate connection line  24  through the thin connection lines  26 , and the drain bus lines  16  are commonly connected to the drain connection line  34  through the thin connection lines  36 , whereby in the processes for fabricating the thin film transistors and the liquid crystal panel, no local charges are present even when electrostatic charges are applied, and electric stresses can be mitigated.  
         [0095]     After the fabrication processes in which electrostatic charges, etc. are applied are over, the thin connection lines  26 ,  36  are melted off by a laser or other to electrically disconnect the gate bus lines  14  from the gate connection line  24  and the drain bus lines  16  from the drain connection line  34 .  
       2. A Second Embodiment  
       [0096]     The thin film transistor matrix device according to a second embodiment of the present invention will be explained with reference to  FIGS. 7 and 8 .  
         [0097]      FIG. 7  shows a pattern layout of the thin film transistor matrix device according to the present embodiment.  FIG. 8  is an enlarged view of the wiring region of the thin film transistor matrix device of  FIG. 7 . The same members and members of the same kinds of the thin film transistor matrix device according to the present embodiment as those of the thin film transistor matrix device according to the first embodiment are represented by common reference numerals to simplify or not to repeat their explanation.  
         [0098]     The thin film transistor matrix device according to the present embodiment is characterized in that adjacent ones  14   a ,  14   b  of a plurality of gate bus lines  14  are respectively commonly connected, and adjacent ones  16   a ,  16   b  of a plurality of drain bus lines  16  are respectively commonly connected.  
         [0099]     As shown in  FIGS. 7 and 8 , a plurality of gate bus lines  14  are divided in odd number-th gate bus lines  14   a  and even number-th gate bus lines.  
         [0100]     The odd number-th gate bus lines  14   a  have bumps  18   a  formed on the ends on the left side as viewed in  FIG. 7  and have the ends on the right side as viewed in  FIG. 7  commonly connected to a gate connection line  24   a . The gate connection line  24   a  is extended along the edge of a transparent insulating substrate  10 .  
         [0101]     The even number-th gate bus lines  14   b  have the bumps  18   b  formed on the ends on the left side as viewed in  FIG. 7 . The bumps  18   b  are commonly connected to the gate connection line  24   b  through thin connection lines  26   b . The gate connection line  24   b  is extended longitudinally in an IC chip region  22  between input terminals  20  and the bumps  18   b.    
         [0102]     Odd number-th drain bus lines  16   a  have bumps  28   a  formed on the ends on the upper side as viewed in  FIG. 7 . The bumps  28   a  are commonly connected to a drain connection line  34   a  through thin connection lines  36   a . The drain connection line  34   a  is extended widthwise in th IC chip region  32  between the input terminals  30  and the bumps  28   a.    
         [0103]     The even number-th drain bus lines  16   b  have the bumps  29   b  formed on the end on the upper side as viewed in  FIG. 7  and the ends on the lower end commonly connected to a drain connection line  34   b . The drain connection line  34   b  is extended along the lower edge of the transparent insulating substrate  10 .  
         [0104]     The gate connection lines  24   a ,  24   b  and the drain connection lines  34   a ,  34   b  are interconnected by resistant lines  38   a ,  38   b ,  38   c ,  38   d . The resistant line  38   a  interconnects the gate connection line  24   a  and the drain connection line  34   a ; the resistant line  38   b  interconnects the gate connection line  24   a  and the drain connection line  34   b ; the resistant line  38   c  interconnects the gate connection line  24   b  and the drain connection line  34   a ; and the resistant line  38   d  interconnects the gate connection line  24   b  and the drain connection line  34   b.    
         [0105]     Thus, according to the present embodiment, the gate bus lines  14   a ,  14   b  are respectively commonly connected to the gate connection lines  24   a ,  24   b . The drain bus lines  16   a ,  16   b  are respectively commonly connected to the drain connection lines  34   a ,  34   b , whereby in the processes for fabricating the thin film transistors and the liquid crystal panel, no local charges are present even when electrostatic charges are applied, and electric stresses can be mitigated.  
         [0106]     For higher inspection precision, a test in which different voltages are applied to adjacent gate bus lines and also to adjacent drain bus lines is preferred to a test in which the same voltage is applied to all the gate bus lines and to all the drain bus lines. According to the present embodiment, adjacent ones  14   a ,  14   b  of the gate bus lines  14  are respectively commonly connected, and adjacent ones  24   a ,  24   b  of the drain bus lines  24  are respectively commonly connected, whereby tests of high precision can be conducted even by applying different voltages to adjacent gate bus lines and also to adjacent drain bus lines.  
       3. A Third Embodiment  
       [0000]     3.1 Thin Film Transistor Matrix Device  
         [0107]     The thin film transistor matrix device according to a third embodiment of the present invention will be explained with reference to FIGS.  9  to  11 .  
         [0108]      FIG. 9  shows a pattern layout of the thin film transistor matrix device according to the present embodiment.  FIG. 10  is an enlarged view of the wiring region of the thin film transistor matrix device of  FIG. 9 .  FIG. 11  is a sectional view of the thin film transistor matrix device of  FIG. 9 . The same members or members of the same kinds of the thin film transistor matrix device according to the present embodiment as those of the thin film transistor matrix device according to the first and the second embodiments are represented by common reference numerals to simplify or not to repeat their explanation.  
         [0109]     The thin film transistor matrix device according to the present embodiment is characterized in that adjacent ones  14   a ,  14   b  of a plurality of gate bus lines  14  are respectively commonly connected, and adjacent ones  16   a ,  16   b  of a plurality of drain bus lines  16  are respectively commonly connected; and gate connection lines  24   a ,  24   b  which commonly connect respectively the gate bus lines  14   a ,  14   b  are arranged on the same side of a transparent insulating substrate, and drain connection lines  34   a ,  34   b  which commonly connect respectively the drain bus lines  16   a ,  16   b  are arranged on the same side of the transparent insulating substrate  10 .  
         [0110]     The plane layout of the thin film transistor matrix device according to the present embodiment will be explained with reference to  FIGS. 9 and 10 .  
         [0111]     A plurality of gate bus lines  14  are divided in odd number-th gate bus lines  14   a  and even number-th gate bus lines  14   b  which are adjacent to each other.  
         [0112]     Bumps  18   a  are formed on the ends of the odd number-th gate bus lines  14   a  on the left side as viewed in  FIG. 9 . The bumps  18   a  are commonly connected to the gate connection line  24   a  through thin connection lines  26   a  and contact holes  27 .  
         [0113]     Bumps  18   b  are formed on the ends of the odd number-th gate base lines  14   b  on the left side as viewed in  FIG. 9 . The bumps  18   b  are commonly connected to the gate connection line  24   b  through thin connection lines  26 .  
         [0114]     The gate connection lines  24   a ,  24   b  are extended longitudinally through an IC chip  22  between input terminals  20  and the bumps  18   a ,  18   b.    
         [0115]     Bumps  28   a  are formed on the ends of the odd number-th bus lines  16   a  on the upper side as viewed in  FIG. 9 . The bumps  28   a  are commonly connected to the drain connection line  34   a  through thin connection lines  36   a  and contact hole  37 .  
         [0116]     Bumps  28   b  are formed on the ends of the even number-th drain bus lines  16   b  on the upper end as viewed in  FIG. 9 . The bumps  28   b  are commonly connected to the drain connection line  34   b  through thin connection lines  36   b.    
         [0117]     The drain connection lines  34   a ,  34   b  are extended transversely through an IC chip region  32  between input terminals  30  and the bumps  28   a ,  28   b.    
         [0118]     The gate connection lines  24   a ,  24   b  and the drain connection lines  34   a ,  34   b  are connected with each other by resistant lines  38   a ,  38   b ,  38   c ,  38   d . The resistant line  38   a  interconnects the gate connection line  24   a  and the gate connection line  24   b ; the resistant line  38   b  interconnects the gate connection line  24   a  and the drain connection line  34   b ; the resistant line  38   c  interconnects the gate connection line  24   b  and the drain connection line  34   a ; and the resistant line  38   d  interconnects the drain connection line  34   a  and the drain connection line  34   b.    
         [0119]     Then, a sectional structure of the thin film transistor matrix device according to the present embodiment will be explained with reference to  FIG. 11 .  
         [0120]     A sectional structure of the vicinity of the drain connection lines  34   a ,  34   b  will be explained with reference to the plan view of  FIG. 10  and the sectional view along the line A-A′.  
         [0121]     A first insulating film  48  is formed on a transparent insulating substrate  10 . On the first insulating film  48 , the thin connection lines  36   b  and the drain connection line  34   a  are formed of the same layer as a semiconductor active layer  50  and a metal active layer  52 . A second insulating film  54  is formed on the metal layer  52 , and the contact holes  37  are formed on the second insulating film  54 . On the second insulating film  54  the drain connection line  34   b  is formed of the same layer as an transparent electrode film. The drain connection line  34   b  is connected to the thin connection lines  36   b  through the contact holes  37 .  
         [0122]     A sectional structure of the vicinity of the gate connection lines  24   a ,  24   b  will be explained with reference to the plan view of  FIG. 10  and the B-B′ sectional view of  FIG. 11 .  
         [0123]     On the transparent insulating substrate  10 , the gate connection line  24   b  and the thin connection lines  26   a  are formed of the same layer as a metal layer  46 . The first and the second insulating films  48 ,  54  are formed on the metal layer  46 . The contact holes  27  are formed in the first and the second insulating films  48 ,  54  on the thin connection lines  26   a . The gate connection line  24   a  is connected to the thin connection lines  26   a  through the contact holes  27 .  
         [0000]     3.2 A First Fabrication Method  
         [0124]     Then, the method for fabricating the thin film transistor matrix device according to the present embodiment will be explained with reference to FIGS.  12  to  17 .  FIGS. 12A-12D  and  13 A- 13 D are A-A′ sectional views and B-B′ sectional views of the thin film transistor matrix device at the respective steps of the first fabrication method. FIGS.  14  to  17  are enlarged plan views of the thin film transistor matrix device at the respective fabrication steps.  
         [0125]     The thin film transistor matrix device according to the present embodiment has the gate connection lines  24   a ,  24   b  formed on the layers which are different from each other but can be fabricated by the use of  5  masks as in the first embodiment.  
         [0126]     The metal layer  46  of, e.g., Al, Cr or others is formed by sputtering on a transparent insulating substrate  10 , such as a glass substrate or others ( FIG. 12A ).  
         [0127]     Then, by the use of a first mask, the metal layer  46  is patterned to form the gate bus lines  14   a ,  14   b , the gate electrodes  42   a , capacitor electrodes  46 , the gate connection line  24   b , the thin connection lines  26   a ,  26   b  and input electrodes  20  ( FIGS. 12B and 14 ).  
         [0128]     Then the first insulating film  48  of an SiN film or a two layer film of an SiO 2  film and an SiN film is formed on the entire surface by plasma CVD.  
         [0129]     Then, on the first insulating film, the semiconductor active layer  50  of non-doped i-type a-Si, and a protection layer (not shown) of an SiO 2  film or an SiN film are continuously formed. Subsequently, by the use of a second mask, all the protection film except part thereof in a TFT region is etched off with a hydrofluoric acid buffer solution.  
         [0130]     Then, an n + -type a-Si layer (not shown) is formed on the entire surface by plasma CVD. Then, the metal layer  52  of Al, Cr or others is formed on the n + -type a-Si layer by sputtering ( FIG. 12C ).  
         [0131]     The, by the use of a third mask, the metal layer  52  and the semiconductor active layer  50  are patterned to form the source electrodes  40   s , the drain electrodes  40   d , the drain bus lines  16   a ,  16   b , the drain connection line  34   a , the thin connection lines  36   a ,  36   b  and input electrodes  30  ( FIGS. 12D and 15 ).  
         [0132]     Then, the second insulating film  54  of an SiN film or a two layer film of an SiO 2  film and an SiN film is formed on the entire surface by plasma CVD ( FIG. 13A ).  
         [0133]     Then, by the use of a fourth mask, the second insulation film  54  and the first insulation film  48  are patterned to form the contact holes  27 , the contact holes  37 , and contact holes for the resistant lines  38  ( FIGS. 13B and 16 ).  
         [0134]     Then, the transparent electrode film  56  is formed on the entire surface by sputtering ( FIGS. 13B and 16 ).  
         [0135]     Next, by the use of a fifth mask, the transparent electrode film  56  is patterned to form picture element electrodes  52 , the gate connection line  34   b , and the resistant lines  38   a ,  38   b ,  38   c ,  38   d  ( FIGS. 13D and 17 ). The resistant lines  38 A,  38 B,  38 C,  38 D are patterned so as to interconnect the ends of the gate connection lines  24   a ,  24   b , and the ends of the drain connection lines  34   a ,  34   b .  
         [0136]     Thus, as in the first embodiment, by the use of only  5  masks, the thin film transistor matrix device according to the present embodiment can be fabricated.  
         [0000]     3.3 A Second Fabrication Method  
         [0137]     Then, another method for fabricating the thin film transistor matrix device according to the present embodiment will be explained with reference to FIGS.  18  to  23 .  FIGS. 18A-18D  and  19 A- 19 C are respectively A-A′ line sectional views and B-B′ sectional views of the thin film transistor matrix device at the respective steps of the second fabrication method. FIGS.  20  to  23  are enlarged plan views of the thin film transistor matrix device at the respective steps of the second fabrication method.  
         [0138]     In the first fabrication method, the contact hole  27  through which the gate connection line  24   a  and the gate connection line  24   b  are connected with each other is formed in the first insulating film  48  and the second insulating film  54 . The gate connection line  24   a  and the gate connection line  24   b  define a too large step therebetween to be well connected with each other.  
         [0139]     By the second fabrication method, one mask is added, whereby large steps are not formed between the lines connected with each other through the contact holes. The present embodiment uses  6  masks, which is  1  mask more than the first embodiment.  
         [0140]     The metal layer  46  of, e.g., Al, Cr or others is formed on a transparent insulating substrate  10 , such as a glass substrate by sputtering ( FIG. 18A ).  
         [0141]     Then, the metal layer  46  is patterned by the use of a first mask to form the gate bus lines  14   a ,  14   b , the gate electrodes  42   a , the capacitor electrodes  46   a , the drain connection line  34   b , the gate connection line  24   b , the thin connection lines  26   a ,  26   b  and the input electrodes  20  ( FIGS. 18B and 20 ).  
         [0142]     Then, the first insulating film  48  of an SiN film, a two-layer film of an SiO 2  film and an SiN film, or others on the entire surface by plasma CVD ( FIG. 18C ).  
         [0143]     Next, on the first insulating film  48 , the semiconductor active layer  48  of non-doped i-type a-Si and the protection film (not shown) of an SiO 2  film or an SiN film are continuously formed by plasma CVD. Subsequently, by the use of a second mask, all the protection film except a part thereof in the TFT channel region is etched off with a hydrofluoric acid buffer solution.  
         [0144]     Then, by the use of an additional mask, the first insulating film  48  is patterned to form the contact holes  37  through which the drain connection line  34   b  and the thin connection lines  36   b  are connected with each other, and the contact holes  27  through which the thin connection lines  26   a  and the gate connection line  24   a  are connected with each other ( FIGS. 18D and 21 ).  
         [0145]     Next, the n + -type a-Si layer (not shown) is formed on the entire surface by plasma CVD. Then, the metal layer  52  of Al, Cr or others is formed on the n + -type a-Si layer by sputtering ( FIG. 19A ).  
         [0146]     Then, by the use of a third mask, the metal layer  52  and the semiconductor active layer  50  are patterned to form the source electrodes  40   s , the drain electrodes  40   d , the drain bus lines  16   a ,  16   b , the drain connection line  34   a , the thin connection lines  36   a ,  36   b , the gate connection line  24   a  and the input electrodes  30  ( FIGS. 19B and 22 ).  
         [0147]     Then, the second insulating film  54  of an SiN film, a two layer film of SiO2 film and an SiN film, or others is formed on the entire surface by plasma CVD ( FIG. 19C ).  
         [0148]     Next, by the use of a fourth mask, the second insulating film  54  and the first insulating film  48  are patterned to form the contact holes for the resistant lines  38 .  
         [0149]     Next, the transparent electrode film  56  is formed on the entire surface by sputtering.  
         [0150]     Then, by the use of a fifth mask, the transparent electrode film  56  is patterned to form the picture element electrodes  42 , and the resistant lines  38   a ,  38   b ,  38   c ,  38   d  ( FIG. 23 ).  
         [0151]     Thus, totally 6 masks including the additional mask are used, whereby the gate connection line  24   a  and the gate connection line  24   b  define a small step therebetween, which enables good connection therebetween.  
         [0152]     Thus, according to the present embodiment, the gate bus lines  14   a ,  14   b  are commonly connected respectively by the gate connection lines  24   a ,  24   b , and the drain bus lines  16   a ,  16   b  are commonly connected respectively by the drain connection lines  34   a ,  34   b , whereby in the process for fabricating the thin film transistors and the process for forming a liquid crystal panel, no local charge is present even when electrostatic charges are applied, whereby electric stresses can be mitigated.  
         [0153]     For higher inspection precision, a test in which different voltages from each other are applied to the gate bus lines which are adjacent to each other and to the drain bus lines which are adjacent to each other is preferred to a test in which the same voltage is applied to all the gate bus lines and all the drain bus lines. According to the present embodiment, the gate bus lines  14   a ,  14   b  which are adjacent to each other are respectively commonly connected, and the drain bus lines  24   a ,  24   b  which are adjacent to each other are respectively commonly connected, whereby different voltages from each other are applied to the adjacent gate bus lines and the drain bus lines for high precision inspection.  
       4. A Fourth Embodiment  
       [0000]     4.1 Thin Film Transistor Matrix Device  
         [0154]     The thin film transistor matrix device according to a fourth embodiment of the present invention will be explained with reference to FIGS.  24  to  26 .  
         [0155]      FIG. 24  is a view of the pattern layout of the thin film transistor matrix device according to the present embodiment.  FIG. 25  is an enlarged view of the wiring region of the thin film transistor matrix device of  FIG. 24 .  FIG. 26  is sectional views of the thin film transistor matrix device of  FIG. 24 . The same members and members of the same kinds of the present embodiment as the thin film transistor matrix device according to the first to the third embodiments are represented by common reference numerals to simplify or not to repeat their explanation.  
         [0156]     In the thin film transistor matrix device according to the present embodiment as well as the third embodiment, gate connection lines  24   a ,  24   b  respectively commonly connecting gate bus lines  14   a ,  14   b  which are adjacent to each other are arranged on the same side of a transparent insulating substrate  10 , and drain connection lines  34   a ,  34   b  respectively commonly connecting drain bus lines  16   a ,  16   b  are arranged on the same side of the transparent insulating substrate  10 , but the present embodiment is different from the third embodiment in the connection structure between the gate bus lines  14   a ,  14   b  and the gate connection lines  24   a ,  24   b  and that between the drain bus lines  16   a ,  16   b  and the drain connection lines  34   a ,  34   b.    
         [0157]     First, a layout of the thin film transistor matrix device according to the present embodiment in a plane will be explained with reference to  FIGS. 24 and 25 .  
         [0158]     A plurality of gate bus lines  14  are divided into odd number-th gate bus lines  14   a  and even number-th gate bus lines  14   b  which are adjacent to each other.  
         [0159]     Bumps  18   a  are formed on the ends of the odd number-th gate bus lines  14   a  on the right side as viewed in  FIG. 24 . The bumps  18   a  are commonly connected to the gate connection line  24   a  through thin connection lines  26   a , contact holes  27   b , a connection line  25  and contact holes  27   a.    
         [0160]     Bumps  18   b  are formed on the ends of the even number-th gate bus lines  14   b  on the left side as viewed in  FIG. 24 . The bumps  18   b  are commonly connected to the gate connection line  24   b  through thin connection lines  26   b.    
         [0161]     The gate connection lines  24   a ,  24   b  are extended longitudinally through an IC chip region  22  between inputs terminals  20  and the bumps  18   a ,  18   b.    
         [0162]     Bumps  28   a  are formed on the ends of the odd number-th drain bus lines  16   a  on the upper end as viewed in  FIG. 24 . The bumps  28   a  are commonly connected to the drain connection line  34   a  through thin connection lines  36   a , contact holes  37   b , a connection line  35  and contact holes  37   a.    
         [0163]     Bumps  28   b  are formed on the ends of the even number-th drain bus lines  16   b  on the upper end as viewed in  FIG. 24 . The bumps  28   b  are commonly connected to the drain connection line  34   s  through thin connection lines  36   b.    
         [0164]     The drain connection lines  34   a ,  34   b  are extended longitudinally through an IC chip region  32  between input terminals  30  and the bumps  28   a ,  28   b.    
         [0165]     Resistant lines  38   a ,  38   b ,  38   c ,  38   d  interconnect the gate connection lines  24   a ,  24   b  and the drain connection lines  34   a ,  34   b . The resistant line  38   a  interconnects the gate connection line  24   a  and the gate connection line  24   b ; the resistant line  38   b  interconnects the gate connection line  24   a  and the drain connection line  34   b ; the resistant line  38   c  interconnects the gate connection line  24   b  and the drain connection line  34   a ; and the resistant line  38   d  interconnects the drain connection line  34   a  and the drain connection line  34   b.    
         [0166]     Then, a sectional structure of the thin film transistor matrix device according to the present embodiment will be explained.  
         [0167]     A sectional structure of the vicinity of the drain connection lines  34   a ,  34   b  will be explained with reference to the plan view of  FIG. 25  and the sectional view along the line A-A′ in  FIG. 26 .  
         [0168]     On a transparent insulating substrate  10 , the drain connection line  34   b  of the same layer as the metal layer  46  is formed. A first insulating film  48  is formed on the transparent insulating film  10  and the drain connection line  34   b . On the first insulating film  48 , the thin connection line  36   b  and the drain connection lines  34   a  of the same layer as the semiconductor active layer  50  and the metal layer  52 . A second insulating film  54  is formed on the metal layer  52 . The contact holes  37   a  are formed in the first and the second insulating films  48 ,  54  and reach the drain connection line  34   b . The contact holes  37   b  are formed in the second insulating film  54  and reach the thin connection lines  36   b . The connection line  35  of the same layer as a transparent electrode film  56  is formed on the second insulating film  54  and interconnects the thin connection lines  36   b  and the drain connection line  34   b  through the contact holes  37   a ,  37   b.    
         [0169]     A sectional structure of the vicinity of the gate connection lines  24   a ,  24   b  will be explained with reference to the plan view of  FIG. 25  and a sectional view along the line B-B′ in  FIG. 26 .  
         [0170]     On the transparent insulating substrate  10 , the gate connection line  24   b  and the thin connection lines  26   a  of the same layer as the metal layer  46  are formed. On the metal layer  46 , the first insulating film  48  is formed. On the first insulating film  48 , the gate connection line  24   a  of the same layer as the semiconductor active layer  50  and the metal layer  52  is formed. The second insulating film  54  is formed on the first insulating film  48  and the gate connection line  24   a . The contact holes  27   a  are formed in the second insulating film  54  and reach the gate connection line  24   a . The contact holes  27   b  are formed in the first and the second insulating films  48 ,  54  and reach the thin connection lines  26   a . On the second insulating film  54 , the connection line  25  of the same layer as the transparent electrode film  56  is formed and interconnects the thin connection lines  26   a  and the gate connection line  24   b  through the contact holes  27   a ,  27   b.    
         [0000]     4.2 Fabrication Method  
         [0171]     Then, the method for fabricating the thin film transistor matrix device according to the present embodiment will be explained with reference to FIGS.  27  to  32 .  FIGS. 27A-27D  and  28 A- 28 D are sectional views of the thin film transistor matrix device according to the present embodiment at the respective step of the fabrication method, which are along the lines A-A′ and the line B-B′. FIGS.  29  to  32  are enlarged plan views of the thin film transistor matrix device at the respective steps of the fabrication method.  
         [0172]     In the present embodiment, although the gate connection lines  24   a ,  24   b  and the drain connection lines  34   a ,  34   b  are formed of the different layers, the thin film transistor matrix device according to the present embodiment can be fabricated by the use of only 5 masks as in the first embodiment.  
         [0173]     First, the metal layer  46  of, e.g., Al. Cr or others is formed on a transparent insulating substrate  10 , such as a glass substrate by sputtering ( FIG. 27A ).  
         [0174]     Next, by the use of a first mask, the metal layer  46  is patterned to form the drain connection line  34   b , the gate bus lines  14   a ,  14   b , gate electrodes  42   a , capacitors  46   a , the gate connection line  24   b , the thin connection lines  26   a ,  26   b , and input electrodes  20  ( FIG. 27B and 29 ).  
         [0175]     The first insulating film  48  of an SiN film, a two-layer film of an SiO 2  film and an SiN film or others is formed on the entire surface by plasma CVD.  
         [0176]     Then, on the insulating film  48 , the semiconductor active layer of non-doped i-type a-Si and a protection film (not shown) of an SiO 2  film or an SiN film are continuously formed. Subsequently by the use of a second mask, all the protection film except a part thereof in a TFT channel region is etched off with a hydrogen fluoride buffer solution.  
         [0177]     Then, an n -type a-Si film (not shown) is formed on the entire surface by plasma CVD. Then, the metal layer  52  of Al, Cr or others is formed on the n + -type a-Si layer by sputtering ( FIG. 27C ).  
         [0178]     Next, by the use of a third mask, the metal layer  52  and the semiconductor active layer  56  are patterned to form source electrodes  40   s , drain electrodes  40   d , the drain bus lines  16   a ,  16   b , the drain connection lines  34   a , the thin connection lines  36   a ,  36   b , input electrodes  30 , and the gate connection line  24   a  ( FIGS. 27D and 30 ).  
         [0179]     Then, the second insulating film  54  of an SiN film, a two-layer film of an SiO 2  film and an SiN film or others is formed on the entire surface by plasma CVD ( FIG. 28A ).  
         [0180]     Next, the second and the first insulating films  54 ,  48  are patterned by the use of a fourth mask to form the contact holes  27   a ,  27   b , the contact holes  37   a ,  37   b  and the contact holes for the resistant lines  38  ( FIGS. 28B and 31 ).  
         [0181]     Then, the transparent electrode film  56  is formed on the entire surface by sputtering ( FIG. 28C ).  
         [0182]     Then, the transparent electrode film  56  is patterned by the use of a fifth mask to form the connection line  35 , picture element electrodes  42 , the gate connection line  24   a , the drain connection line  34   b , the resistant lines  38   a ,  38   b ,  38   b ,  38   d , and the connection line  25  ( FIGS. 28D and 32 ). The resistant lines  38   a ,  38   b ,  38   c ,  38   d  are patterned so as to interconnect the ends of the gate connection lines  24   a ,  24   b  and the ends of the drain connection lines  34   a ,  34   b.    
         [0183]     Thus, by the use of only 5 masks, the thin film transistor matrix device according to the present embodiment can be fabricated as the first embodiment.  
         [0184]     As described above, according to the present embodiment, the gate bus lines  14   a ,  14   b  are commonly connected to the gate connection lines  24   a ,  24   b , and the drain bus lines  16   a ,  16   b  are commonly connected to the drain connection lines  34   a ,  34   b , whereby in the process for fabricating the thin film transistor matrix device and the process for forming a liquid crystal panel, even when electrostatic charges are applied, no local presence of charges, and electric stresses can be mitigated.  
         [0185]     For higher inspection precision, a test in which different voltages are applied to adjacent gate bus lines and also to adjacent drain bus lines is preferred to a test in which the same voltage is applied to all the gate bus lines and to all the drain bus lines. According to the present embodiment, adjacent ones  14   a ,  14   b  of the gate bus lines  14  are respectively commonly connected, and adjacent ones  24   a ,  24   b  of the drain bus lines  24  are respectively commonly connected, whereby tests of high precision can be conducted even by applying different voltages to adjacent gate bus lines and also to adjacent drain bus lines.  
       5. A Fifth Embodiment  
       [0186]     The thin film transistor matrix device according to a fifth embodiment of the present invention will be explained with reference to  FIGS. 33 and 34 .  
         [0187]      FIG. 33  is a view of a pattern layout of the thin film transistor matrix device according to the present embodiment.  FIG. 34  is an enlarged view of the wiring region of the thin film transistor matrix device of  FIG. 33 . The same members or members of the same kinds of the present embodiment as the first to the fourth embodiments are represented by common reference numerals to simplify or not to repeat their explanation.  
         [0188]     In the thin film transistor matrix device according to the present embodiment, gate connection lines  24   a ,  24   b  which respectively commonly connect gate bus lines  14   a ,  14   b , and a drive circuit on the gate side are arranged on both sides of a transparent insulating substrate  10 , and drain connection lines  34   a ,  34   b  which respectively commonly connect drain bus lines  16   a ,  16   b , and a drive circuit for the drain side are arranged on both sides of the transparent insulating substrate  10 .  
         [0189]     A plurality of gate bus lines  14  are divided into odd number-th gate bus lines  14   a  and even number-th gate bus lines  14   b.    
         [0190]     Bumps  18   a  are formed on the ends of the odd number-th gate bus lines  14   a  on the right side as viewed in  FIG. 33 . Input terminals  20   a  for receiving signals from the outside are formed on the right margin of the transparent insulating substrate  10 . The gate connection line  24   a  is extended longitudinally through an IC chip region  22  between the gate connection line  24   a , and the input terminals  20   a  and the bumps  18   a.    
         [0191]     Bumps  18   b  are formed on the ends of the even number-th gate bus lines  14   b  on the left side as viewed in  FIG. 33 . Input terminals  20   b  for receiving signals from the outside are formed on the left margin of the transparent insulating substrate  10 . The gate connection line  24   b  is extended longitudinally through an IC chip region  22  between the input terminals  20   b  and the bumps  18   b.    
         [0192]     Bumps  28   a  are formed on the ends of the odd number-th drain bus lines  16   a  on the upper side as viewed in  FIG. 33 . Input terminals  30   a  for receiving signals from the outside are formed on the upper margin of the transparent insulating substrate  10 . The gate connection line  34   a  is extended longitudinally through an IC chip region  32  between the input terminals  30   a  and the bumps  28   a.    
         [0193]     Bumps  28   b  are formed on the ends of the even number-th drain bus lines  16   b  on the lower end as viewed in  FIG. 33 . Input terminals  30   b  for receiving signals from the outside are formed on the lower margin of the transparent insulating substrate  10 . The gate connection line  34   b  is extended longitudinally through an IC chip region between the input terminals  30   b  and the bumps  28   b.    
         [0194]     Resistant lines  38   a ,  38   b ,  38   c ,  38   d  interconnect the gate connection lines  24   a ,  24   b  and the drain connection lines  34   a ,  34   b . The resistant line  38   a  interconnects the gate connection line  24   a  and the drain connection line  34   a ; the resistant connection line  38   b  interconnects the gate connection line  24   a  and the drain connection line  34   b ; the resistant line  38   c  interconnects the gate connection line  24   b  and the drain connection line  34   a ; and the resistant line  38   d  interconnects the gate connection line  24   b  and the drain connection line  34   b.    
         [0195]     As described above, the gate bus lines  14   a ,  14   b  are respectively commonly connected to the gate connection lines  24   a ,  24   b , and the drain bus lines  16   a ,  16   b  are respectively commonly connected to the drain connection lines  34   a ,  34   b , whereby in the process for fabricating the thin film transistor matrix device and in the process for forming a liquid crystal panel, even when electrostatic charges are applied, there is no local presence of charges, and electric stresses can be mitigated. Furthermore, according to the present embodiment, the gate bus lines  14   a ,  14   b  which are adjacent to each other are respectively commonly connected to the gate connection lines, and the drain bus lines  24   a ,  24   b  which are adjacent to each other are respectively commonly connected to the drain connection lines, whereby different voltages are applied to the gate bus lines which are adjacent to each other and to the drain bus lines which are adjacent to each other, whereby inspection of high precision can be conducted.  
       6. Variations  
       [0196]     The present invention is not limited to the above-described embodiments and includes other variations.  
         [0197]     For example, in the above-described embodiments, the present invention is applied to inverse-staggered TFT matrix device but is also applicable to devices of other device structures, such as staggered TFT matrix devices.  
         [0198]     In the above-described embodiments, the gate bus lines and the drain bus lines are respectively grouped as even-number-th ones and odd number-th ones to be connected to the respective connection lines by group, but the present invention is not limited to this connection mode. The gate bus lines and the drain bus lines may be grouped in other combinations to be commonly connected to the connection lines.