Method to prevent static destruction of an active element comprised in a liquid crystal display device

Abstract

A liquid crystal display device which utilizes an active matrix substrate and its substrate, and which is provided with a novel method of manufacture which can reduce the manufacturing process of amorphous silicon thin film transistors of reverse stagger construction, and an electrostatic protection means which is created using this method of manufacture. In a thin film transistor manufacturing process, along with forming an aperture for connecting the contact hole and the external terminal in a manufacturing process for a thin film transistor, utilization is made of ITO film as the wiring. The electrostatic protection means is formed from a bi-directional diode (electrostatic protection element) which is composed utilizing an MOS transistor connected between the electrode (PAD) for connecting the external terminal, and the joint electric potential line. The electrostatic protection element is substantially a transistor, with great current capacity, and utilizing the TFT formation process of pixel components in their existent state, the process can be formed without any complications.

What is claimed is:  
     
         1 . An active matrix substrate, comprising: 
 a scanning line;    a signal line;    a pixel electrode;    a thin film transistor electrically connected to the scanning line, the signal line arranged in a matrix state and the pixel electrode to compose pixel components;    a protective circuit to prevent static electricity destruction using the thin film transistor established between at least one of the scanning line and the signal line, or a region electrically equivalent to the at least one of the scanning line and the signal line, and a common electric potential wiring other than the scanning line and the signal line, the protective circuit to prevent electrostatic destruction including a diode wherein a gate electrode layer in the thin film transistor and a source/drain electrode layer are connected; and    a first aperture formed by selectively removing an insulation layer on the gate electrode layer and a second aperture formed in a same manufacturing process by selectively removing an insulation layer on the source/drain electrode layer, the gate electrode layer and the source/drain electrode layer being electrically connected via the first aperture and second aperture by an electrically conductive material layer composed of the same material as the pixel electrode.    
     
     
         2 . The active matrix substrate of  claim 1 , the first aperture passing through the overlapping film of the first insulation film on the gate electrode material layer and passing through the second insulation film on the first insulation film, and the second aperture passing through only the second insulation film on the source/drain electrode layer.  
     
     
         3 . The active matrix substrate of  claim 1 , the pixel electrode and the electrically conductive material layer being formed from ITO (indium tin oxide) film.  
     
     
         4 . The active matrix substrate of  claim 1 , a region electrically equivalent to at least one of the scanning line and the signal line being an electrode to connect the external terminal, and one of a common electric potential line which applies a standard potential that becomes the standard potential at a time of driving the liquid crystal using alternate current, and a joint electric potential line to commonly connect the electrode to make the electrode and the one of the common electric potential line and the joint electric potential line the same electric potential.  
     
     
         5 . The active matrix substrate of  claim 4 , the protective circuit to prevent static electricity destruction being provided both between the electrode to connect the external terminal and the common electric potential line and between the electrode to connect the external terminal and the joint electric potential line.  
     
     
         6 . The active matrix substrate of  claim 1 , the protective circuit to prevent static electricity destruction including a bi-directional diode to commonly connect a first diode anode and a second diode cathode, to commonly connect a first diode cathode and a second diode anode.  
     
     
         7 . The active matrix substrate of  claim 1 , the region electrically equivalent being formed with a common electric potential line.  
     
     
         8 . The active matrix substrate of  claim 7 , the common electric potential line being electrically connected to a plurality of scanning lines and a plurality of signal lines.  
     
     
         9 . The active matrix substrate of  claim 7 , the common electric potential line being electrically connected to a facing electrode.  
     
     
         10 . The active matrix substrate of  claim 7 , the common electric potential line having a gate electrode material wiring, a source material wiring, and a pixel electrode material connected between the gate electrode material wiring and the source material wiring.  
     
     
         11 . A liquid crystal display device, comprising: 
 the active matrix substrate of  claim 1 .    
     
     
         12 . A method of preventing electrostatic destruction of active elements in an active matrix liquid crystal display device, the method comprising: 
 forming a pixel part including a thin film transistor connected to a scanning line and a signal line arranged in a matrix, and a pixel electrode connected to one end of the thin film transistor;    providing protective circuit to prevent electrostatic destruction, including a diode having a gate electrode layer in the thin film transistor connected to a source/drain electrode layer; and    connecting the protective device to prevent static electricity destruction between at least one of the scanning line, the signal line, a member electrically equivalent to at least one of said scanning line and the signal line, and a common electric potential line other than the scanning line and the signal line.    
     
     
         13 . The method of  claim 12 , the common electric potential line having a gate electrode material wiring, a source material wiring, and a pixel electrode material connected between the gate electrode material wiring and the source material wiring.  
     
     
         14 . An active matrix substrate, comprising: 
 a scanning line;    a signal line;    a thin film transistor disposed in correspondence with intersections of the scanning line and the signal line;    a pixel electrode disposed in correspondence with the thin film transistor; and    a protective element to prevent static electricity destruction electrically connected between at least one of the scanning line and the signal line, and a common electric potential line, the protective element at least in part forming a pixel electrode material layer.    
     
     
         15 . The active matrix substrate of  claim 14 , at least one of the scanning line and the signal line being electrically connected to an electrode to connect an external terminal, the protective element being electrically connected between the common electric potential line and the electrode to connect the external terminal.  
     
     
         16 . The active matrix substrate of  claim 14 , the protective element using the thin film transistor.  
     
     
         17 . The active matrix substrate of  claim 16 , one of a source electrode and a drain electrode of the thin film transistor for the protective element being electrically connected to one of the scanning line and the signal line via the pixel electrode material layer.  
     
     
         18 . The active matrix substrate of  claim 16 , the protective element including a diode that is formed from the thin film transistor electrically connected between a gate electrode and one of a source electrode and a drain electrode.  
     
     
         19 . The active matrix substrate of  claim 18 , one of a source electrode and a drain electrode of the thin film transistor for the protective element being electrically connected to one of the scanning line and the signal line via the pixel electrode material layer.  
     
     
         20 . The active matrix substrate of  claim 18 , a gate electrode of the thin film transistor for the protective element being electrically connected to one of the source electrode and the drain electrode of the thin film transistor via the pixel electrode material layer.  
     
     
         21 . The active matrix substrate of  claim 16 , the protective element including a first diode formed from the connection of the gate electrode and a drain electrode of a first thin film transistor, and a second diode formed from the connection of the gate electrode and a drain electrode of a second thin film transistor, the first diode and the second diode being connected mutually in a reverse direction, in parallel.  
     
     
         22 . The active matrix substrate of  claim 14 , the common electric potential line being electrically connected to a facing electrode.  
     
     
         23 . The active matrix substrate of  claim 22 , the common electric potential line being electrically connected to a pad to connect a facing electrode via the pixel electrode material layer.  
     
     
         24 . A liquid crystal display device, comprising: 
 the active matrix substrate of  claim 14.