Patent Publication Number: US-2018040508-A1

Title: Tft structure and repair method thereof, goa circuit

Description:
FIELD OF THE INVENTION 
     The present invention relates to a display technology field, and more particularly to a TFT structure and a repair method thereof, a GOA circuit. 
     BACKGROUND OF THE INVENTION 
     The Liquid Crystal Display (LCD) possesses advantages of thin body, power saving and no radiation to be widely used in many application scope, such as LCD TV, mobile phone, personal digital assistant (PDA), digital camera, notebook, laptop, and dominates the flat panel display field. 
     Most of the liquid crystal displays on the present market are backlight type liquid crystal displays, which comprise a liquid crystal display panel and a backlight module. The working principle of the liquid crystal display panel is that the Liquid Crystal is injected between the Thin Film Transistor Array Substrate (TFT array substrate) and the Color Filter (CF). The light of backlight module is refracted to generate images by applying driving voltages to the two substrates for controlling the rotations of the liquid crystal molecules. 
     The Active Matrix Liquid Crystal Display (AMLCD) is the most common liquid crystal display at present. The Active Matrix Liquid Crystal Display comprises a plurality of pixels, and each pixel is controlled by one Thin Film Transistor (TFT). The gate of the TFT is coupled to the scan line extending along the horizontal direction. The drain of the TFT is coupled to the data line extending along the vertical direction. The source is coupled to the corresponding pixel electrode. When a sufficient positive voltage is applied to some scan line in the horizontal direction, all the TFT coupled to the scan line will be activated to write the data signal loaded in the data line into the pixel electrodes and thus to show images to control the transmittances of different liquid crystals to achieve the effect of controlling colors. 
     The driving of the level scan line (i.e. the gate driving) in the present active matrix liquid crystal display is initially accomplished by the external Integrated Circuit (IC). The external IC can control the charge and discharge stage by stage of the level scan lines of respective stages. The GOA technology, i.e. the Gate Driver on Array technology can utilize the array manufacture processes of the liquid crystal display panel to manufacture the driving circuit of the level scan lines on the substrate around the active area, to replace the external IC for accomplishing the driving of the level scan lines. The GOA technology can reduce the bonding procedure of the external IC and has potential to raise the productivity and lower the production cost. Meanwhile, it can make the liquid crystal display panel more suitable to the narrow frame design of display products. 
     The GOA circuit comprises a plurality of TFTs.  FIG. 1  shows a TFT structure in a GOA circuit according to prior art, comprising a comb source constructed by a plurality of U shape source branches  11  connected with one another, and a drain constructed by strip drain branches  12  of the same amount as the plurality of U shape source branches  11 . One strip drain branch  12  is set to correspond to the opening of one U shape source branch  11 . The U shape source branch  11  comprises a transverse part  111  and two longitudinal parts  112  perpendicularly connected to the transverse part  111 . The transverse parts  111  of the plurality of U shape source branches  11  are connected to be one body. The two adjacent U shape source branches  11  share one longitudinal part  112 ; the plurality of strip drain branches  12  are connected to the same metal line, and the all the plurality of U shape source branches  11  are connected to another metal line through the same connection part  113 . In the TFT structure shown in  FIG. 1 , as the defect appears in one U shape source branch  11  and the corresponding strip drain branch  12 , it results in the electrical failure of the entire TFT and cannot be repaired. Thus, the logic error happens in the GOA circuit utilizing the TFT structure, and even the waste of the entire panel. 
     SUMMARY OF THE INVENTION 
     An objective of the present invention is to provide a TFT substrate structure, which is easy to repair. 
     Another objective of the present invention is to provide a repair method of a TFT, which can effectively repair the defect of the TFT and raise the repair success rate. 
     Another objective of the present invention is to provide a GOA circuit, which can promote the manufacture yield of the GOA circuit and reduce the production cost of the GOA circuit. 
     For realizing the aforesaid objectives, the present invention provides a TFT structure, comprising a source, a drain oppositely located to the source, and a gate, located above or under the source and the drain, and mutually isolated with the source and the drain; 
     the source comprises a plurality of U shape source branches, spaced and aligned along a first direction, and the drain comprises a plurality of strip drain branches, spaced and aligned along the first direction; 
     one strip drain branch is located inside an opening of one independent U shape source branch; 
     each independent U shape source branch is solely connected to a first metal line with a connection part; all the plurality of strip drain branches are electrically coupled to a second metal line. 
     Each independent U shape source branch comprises a transverse part extending along the first direction, and two longitudinal parts perpendicularly connected to two ends of the transverse part. 
     Each connection part is drew out from the transverse part of the independent U shape source branch corresponding thereto, and extends to the first metal line to achieve a sole connection of each independent U shape source branch and the first metal line. 
     The strip drain branch is parallel with the longitudinal part of the independent U shape source branch. 
     The TFT structure further comprises an active layer located under the source and the drain. 
     The present invention further provides a repair method of a TFT, comprising steps of: 
     step 1, providing a TFT, comprising a source, a drain oppositely located to the source, and a gate, located above or under the source and the drain, and mutually isolated with the source and the drain; 
     the source comprises a plurality of U shape source branches, spaced and aligned along a first direction, and the drain comprises a plurality of strip drain branches, spaced and aligned along the first direction; 
     one strip drain branch is located inside an opening of one independent U shape source branch; 
     each independent U shape source branch is solely connected to a first metal line with a connection part; all the plurality of strip drain branches are electrically coupled to a second metal line; 
     step 2, detecting whether the respective independent U shape source branches and the corresponding strip drain branches in the TFT have defects or not to find out the independent U shape source branch and the corresponding strip drain branch having a defect; 
     step 3, cutting a connection between the independent U shape source branch having the defect and the first metal line, and cutting a connection between the corresponding strip drain branch and the second metal line. 
     Each independent U shape source branch comprises a transverse part extending along the first direction, and two longitudinal parts perpendicularly connected to two ends of the transverse part; 
     The strip drain branch is parallel with the longitudinal part of the independent U shape source branch. 
     Each connection part is drew out from the transverse part of the independent U shape source branch corresponding thereto, and extends to the first metal line to achieve a sole connection of each independent U shape source branch and the first metal line; 
     in the step 3, cutting the connection between the independent U shape source branch having the defect and the first metal line is to cut the corresponding connection part. 
     An active layer is further located under the source and the drain. 
     The present invention further provides a GOA circuit, comprising the aforesaid TFT structure. 
     The benefits of the present invention are: the present invention provides a TFT structure and a repair method thereof. The TFT comprises a source having a plurality of U shape source branches, spaced and aligned along a first direction, and a drain having a plurality of strip drain branches, spaced and aligned along the first direction. Each independent U shape source branch is solely connected to a first metal line with a connection part, and all the plurality of strip drain branches are electrically coupled to a second metal line. The respective independent U shape source branches and the corresponding strip drain branches construct a plurality of independent source-drain conduction channels, and the respective independent source-drain conduction channels do not influence with one another. As some independent U shape source branch and the corresponding strip drain branch is detected having a defect, the repair can be implemented by cutting the connection between the independent U shape source branch and the first metal line, and cutting the connection between corresponding strip drain branch and the second metal line. Namely, the source-drain conduction channel having a defect is cut, and other source-drain conduction channels can remain working normally. Accordingly, the defect of the TFT can be effectively repaired to raise the repair success rate. The present invention provides a GOA circuit, comprising the aforesaid TFT structure, can promote the manufacture yield of the GOA circuit and reduce the production cost of the GOA circuit. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In order to better understand the characteristics and technical aspect of the invention, please refer to the following detailed description of the present invention is concerned with the diagrams, however, provide reference to the accompanying drawings and description only and is not intended to be limiting of the invention. 
       In drawings, 
         FIG. 1  is a diagram of a TFT structure in a GOA circuit according to prior art; 
         FIG. 2  is a diagram of a TFT structure of the present invention; 
         FIG. 3  is a flowchart of a repair method of a TFT according to the present invention; 
         FIG. 4  is a diagram of the step 3 of the repair method of the TFT according to the present invention. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     For better explaining the technical solution and the effect of the present invention, the present invention will be further described in detail with the accompanying drawings and the specific embodiments. 
     Please refer to  FIG. 2 . The present invention first provides a TFT structure, comprising a source  10 , a drain  20  oppositely located to the source  10 , and a gate (not shown in figure), located above or under the source  10  and the drain  20 , and mutually isolated with the source  10  and the drain  20 . 
     The source  10  comprises a plurality of U shape source branches  101 , spaced and aligned along a first direction, and the drain  20  comprises a plurality of strip drain branches  201 , spaced and aligned along the first direction. One strip drain branch  201  is located inside an opening of one independent U shape source branch  101 . 
     Each independent U shape source branch  101  is solely connected to a first metal line  30  with a connection part  103 ; all the plurality of strip drain branches  201  are electrically coupled to a second metal line  40 . 
     Specifically, each independent U shape source branch  101  comprises a transverse part  1011  extending along the first direction, and two longitudinal parts  1012  perpendicularly connected to two ends of the transverse part  1011 . The strip drain branch  201  is parallel with the longitudinal part  1012  of the independent U shape source branch  101 . 
     Each connection part  103  is drew out from the transverse part  1011  of the independent U shape source branch  101  corresponding thereto, and extends to the first metal line  30  to achieve a sole connection of each independent U shape source branch  101  and the first metal line  30 . 
     Preferably, the first metal line  30  and the second metal line  40  are mutually parallel and spaced, and the first direction is the horizontal direction, and the transverse part  1011  extends horizontally, and the longitudinal part  1012  extends vertically, and the first and second metal lines  30 ,  40  extends horizontally, and the strip drain branch  201  extends vertically. 
     The TFT structure further comprises an active layer (not shown in figure) located under the source  10  and the drain  20 . 
     Selectably, the TFT structure is a bottom gate type or a top gate type: as the TFT structure is the bottom gate type, the gate is under the source  10  and the drain  20 ; as the TFT structure is the top gate type, the gate is above the source  10  and the drain  20 . 
     Selectably, material of the source  10 , the drain  20  and the gate is a stack combination of one or more of copper, aluminum, molybdenum and titanium. 
     Selectably, the active layer is N-type doped or P-type doped. 
     In the aforesaid TFT structure, the gate is employed to receive a switch signal to control on and off of all the independent U shape source branches  101  and the corresponding strip drain branches  201 . Significantly, the respective independent U shape source branches  101  and the corresponding strip drain branches  201  construct a plurality of independent source-drain conduction channels, and the disconnection of any one of the source-drain conduction channels does not influence the other source-drain conduction channels. Thus, as some independent U shape source branch  101  and the corresponding strip drain branch  201  are detected having a defect (such as short circuit), the repair can be implemented by cutting the connection between the independent U shape source branch  101  and the first metal line  30 , and cutting the connection between corresponding strip drain branch  201  and the second metal line  40 . Namely, the source-drain conduction channel having a defect is disconnected, and other source-drain conduction channels can remain working normally. Therefore, the TFT structure of the present invention can be easily repaired. 
     Please refer to  FIG. 3  combining with  FIG. 2 ,  FIG. 4 , the present invention further provides a repair method of a TFT, comprising steps of: 
     step 1, providing a TFT shown in  FIG. 2 . The description of the TFT structure is not repeated here. 
     step 2, detecting whether the respective independent U shape source branches  101  and the corresponding strip drain branches  201  in the TFT have defects or not to find out the independent U shape source branch  101  and the corresponding strip drain branch  201  having a defect. 
     step 3, as shown in  FIG. 4 , cutting a connection between the independent U shape source branch  101  having the defect and the first metal line  30 , and cutting a connection between the corresponding strip drain branch  201  and the second metal line  40 . 
     Specifically, cutting the connection between the independent U shape source branch  101  having the defect and the first metal line  30  is to cut the corresponding connection part  103 . 
     In the repair method of the TFT according to the present invention, the TFT comprises a source  10  having a plurality of U shape source branches  101 , spaced and aligned along a first direction, and a drain  20  having a plurality of strip drain branches  201 , spaced and aligned along the first direction. Each independent U shape source branch  101  is solely connected to a first metal line  30  with a connection part  103 , and all the plurality of strip drain branches  201  are electrically coupled to a second metal line  40 . The respective independent U shape source branches  101  and the corresponding strip drain branches  201  construct a plurality of independent source-drain conduction channels, and the respective independent source-drain conduction channels do not influence with one another. As some independent U shape source branch  101  and the corresponding strip drain branch  201  are detected having a defect, the repair can be implemented by cutting the connection between the independent U shape source branch  101  and the first metal line  30 , and cutting the connection between corresponding strip drain branch  201  and the second metal line  40 . Namely, the source-drain conduction channel having a defect is cut, and other source-drain conduction channels can remain working normally. Accordingly, the defect of the TFT can be effectively repaired to raise the repair success rate. 
     The present invention further provides a GOA circuit, comprising the TFT structure shown in  FIG. 2 . Compared with the GOA circuit of prior art utilizing the TFT structure which cannot repair, the structure can promote the manufacture yield of the GOA circuit and reduce the production cost of the GOA circuit. 
     In conclusion, in the TFT structure and a repair method thereof according to the present invention, the TFT comprises a source having a plurality of U shape source branches, spaced and aligned along a first direction, and a drain having a plurality of strip drain branches, spaced and aligned along the first direction. Each independent U shape source branch is solely connected to a first metal line with a connection part, and all the plurality of strip drain branches are electrically coupled to a second metal line. The respective independent U shape source branches and the corresponding strip drain branches construct a plurality of independent source-drain conduction channels, and the respective independent source-drain conduction channels do not influence with one another. As some independent U shape source branch and the corresponding strip drain branch is detected having a defect, the repair can be implemented by cutting the connection between the independent U shape source branch and the first metal line, and cutting the connection between corresponding strip drain branch and the second metal line. Namely, the source-drain conduction channel having a defect is cut, and other source-drain conduction channels can remain working normally. Accordingly, the defect of the TFT can be effectively repaired to raise the repair success rate. The GOA circuit of the present invention comprises the aforesaid TFT structure, and can promote the manufacture yield of the GOA circuit and reduce the production cost of the GOA circuit. 
     Above are only specific embodiments of the present invention, the scope of the present invention is not limited to this, and to any persons who are skilled in the art, change or replacement which is easily derived should be covered by the protected scope of the invention. Thus, the protected scope of the invention should go by the subject claims.