TFT LCD device having multi-layered pixel electrodes

Abstract

In a TFT LCD device comprising a substrate, at least one thin film transistor formed on the substrate, having a source electrode and a drain electrode, an insulating layer formed over the whole surface of the substrate on which the thin film transistor is formed, having at least one contact hole exposing a portion of the drain electrode, and reflective layer pixel electrode corresponding to the thin film transistor, formed on the insulating layer to be connected with the drain electrode through the contact hole, the pixel electrode is formed of a multi-layered conductive layer. The drain electrode is composed of multiple layers, and the most upper layer of the multiple layers is one selected from a Cr layer and a MoW layer. Preferably, the multi-layered conductive layer is composed of two-layered conductive layer having a lower layer of the same material as that of the most upper layer and an upper layer of Al-containing metal.

1. A thin film transistor liquid crystal device (TFT LCD), comprising:
 a substrate;  
 a thin film transistor  TFT formed on said substrate and having a source electrode and a drain electrode, wherein the drain electrode is formed of multiple layers comprising an uppermost layer formed of Cr or MoW;  
 an insulating layer formed over said thin film transistor  TFT formed of a photosensitive insulating material and having a contact hole exposing a portion of the drain electrode; and  
 a pixel electrode formed on said insulating layer, and connected to the drain electrode through the contact hole, wherein the pixel electrode is formed of multiple layers comprising a lower layer formed of the same material as the uppermost layer of the drain electrode and an upper layer formed of metal containing Al,  
   wherein the pixel electrode further comprises a intermediate layer formed between the lower layer and the upper layer and formed of a material having an electro - negativity ranging between that of the lower layer and that of the upper layer.    
 
     
     
       2. The TFT LCD according to  claim 1 , wherein the pixel electrode further comprises an intermediate layer formed between the upper layer and the lower layer and formed of a material having an electro-negativity that is between that of the lower layer and that of the upper layer. 
     
     
       3. The TFT LCD according to  claim 1 ,  A thin film transistor liquid crystal device ( TFT LCD ) , comprising:  
   a substrate;    
   a TFT formed on said substrate and having a source electrode and a drain electrode, wherein the drain electrode is formed of multiple layers comprising an uppermost layer formed of Cr or MoW;    
   an insulating layer formed over said TFT, formed of a photosensitive insulating material and having a contact hole exposing a portion of the drain electrode; and    
   a pixel electrode formed on said insulating layer, and connected to the drain electrode through the contact hole, wherein the pixel electrode is formed of multiple layers comprising a lower layer formed of the same material as the uppermost layer of the drain electrode and an upper layer formed of metal containing Al,  wherein the drain electrode is formed of multiple layers further comprisescomprising a lower layer formed of MoWand , an intermediate metal layer containing Al, and the uppermost layer formed of Cr or MoW.  
 
     
     
       4. The TFT LCD according to  claim 1 , wherein said thin film transistor is a top-gate type polysilicon thin film transistor. 
     
     
       5. The TFT LCD according to  claim 1 , wherein said insulating layer is formed of a photo-sensitive organic insulating layer. 
     
     
       6. The TFT LCD according to  claim 1 , further comprising a plurality of small projections formed on an upper surface of said insulating layer and works as micro lens. 
     
     
       7. A thin film transistor liquid crystal device (TFT LCD), comprising:
 a substrate;    a thin film transistor formed on said substrate and having a source electrode and a drain electrode, wherein the drain electrode is formed of Cr or MoW;    an insulating layer formed over said thin film transistor and having a contact hole exposing a portion of the drain electrode; and    a pixel electrode formed on said insulating layer and connected to the drain electrode through the contact hole,    wherein said pixel electrode is multi-layered and comprises a lower layer formed of the same material as the drain electrode.    
     
     
       8. The TFT LCD of  claim 7 , wherein the pixel electrode further comprises an upper layer formed of metal containing Al. 
     
     
       9. The TFT of  claim 7 , wherein the pixel electrode further comprises  A thin film transistor liquid crystal device ( TFT LCD ) , comprising:  
   a substrate;    
   a TFT formed on said substrate and having a source electrode and a drain electrode, wherein the drain electrode is formed of multiple layers comprising an uppermost layer formed of Cr or MoW;    
   an insulating layer formed over said TFT having a contact hole exposing a portion of the drain electrode; and    
   a pixel electrode formed on said insulating layer and connected to the drain electrode through the contact hole, wherein said pixel electrode is multi - layered and comprises a lower layer formed of same material as the uppermost layer of the drain electrode, an upper layer formed of metal containing Al, and    
 an intermediate layer formed between the upper layer and the lower layer and formed of a material having an electro-negativity ranging  that is between that of the lower layer and that of the upper layer.  
 
     
     
       10. The TFT LCD according to  claim 7 ,  A thin film transistor liquid crystal device ( TFT LCD ) , comprising:  
   a substrate;    
   a TFT formed on said substrate and having a source electrode and a drain electrode, wherein the drain electrode is formed of multiple layers comprising an uppermost layer formed of Cr or MoW;    
   an insulating layer formed over said TFT having a contact hole exposing a portion of the drain electrode; and    
   a pixel electrode formed on said insulating layer and connected to the drain electrode through the contact hole, wherein said pixel electrode is multi-layered and comprises a lower layer formed of same material as the uppermost layer of the drain electrode; and    
 wherein the drain electrode is multi-layered and comprises an upper  the uppermost layer formed of Cr or MoW, a lower layer formed of MoW and an intermediate metal layer containing Al.  
 
     
     
       11. The TFT LCD according to  claim 7 , wherein said thin film transistor is a top-gate type polysilicon thin film transistor. 
     
     
       12. The TFT LCD according to  claim 7 , wherein said insulating layer is formed of a photo-sensitive organic insulating layer. 
     
     
       13. The TFT LCD according to  claim 7 , further comprising a plurality of small projections formed on an upper surface of said insulating layer and works as micro lens. 
     
     
       14. A thin film transistor liquid crystal device ( TFT LCD ) , comprising:      a substrate;        a TFT formed on the substrate and having a source electrode and a drain electrode, wherein the drain electrode is formed of multiple layers comprising an uppermost layer formed of Cr or MoW;        an insulating layer formed over said TFT and having a contact hole exposing a portion of the drain electrode; and        a pixel electrode formed on the insulating layer, wherein the pixel electrode is formed of multiple layers comprising:        a lower layer formed of a same metal as the uppermost layer and in contact with the drain electrode through the contact hole, and        a upper layer formed over the lower layer and formed of a different metal from the uppermost layer;        wherein the pixel electrode further comprises an intermediate layer formed between the lower layer and the upper layer and formed of a material having an electro - negativity ranging between that of the lower layer and that of the upper layer.      
     
     
       15. A thin film transistor liquid crystal device ( TFT LCD ) , comprising:      a substrate;        a TFT formed on the substrate and having a source electrode and a drain electrode,        wherein the drain electrode is formed of multiple layers comprising an uppermost layer formed of Cr or Mo;        an insulating layer formed over said TFT and having a contact hole exposing a portion of the drain electrode; and        a pixel electrode formed on the insulating layer, wherein the pixel electrode is formed of multiple layers comprising:        a lower layer formed of a same metal as the uppermost layer and in contact with the drain electrode through the contact hole, and        an upper layer formed over the lower layer and formed of a different metal from the uppermost layer;        wherein the drain electrode is formed of multiple layers comprising:        the uppermost layer formed of Cr or MoW,        a second electrode layer formed of Al and formed under a first electrode layer, and        a third electrode layer formed of MoW and formed under the second electrode layer.