Thin film transistor, method of manufacturing the same, and organic light emitting diode display device including the same

Abstract

A thin film transistor for an organic light emitting diode includes a substrate including a pixel portion and an interconnection portion, a buffer layer on the substrate, a gate electrode and a gate interconnection on the buffer layer, wherein the gate electrode is located at the pixel portion and the gate interconnection is located at the interconnection portion, a gate insulating layer on the substrate, a semiconductor layer on the gate electrode, source and drain electrodes electrically connected to the semiconductor layer, and a metal pattern on the gate interconnection.

1 . A thin film transistor comprising:
 a substrate including a pixel portion and an interconnection portion;   a buffer layer on the substrate;   a gate electrode and a gate interconnection on the buffer layer, the gate electrode being located at the pixel portion, the gate interconnection being located at the interconnection portion;   a gate insulating layer on the substrate;   a semiconductor layer on the gate electrode;   source and drain electrodes electrically connected to the semiconductor layer; and   a metal pattern on the gate interconnection.   
   
   
       2 . The thin film transistor of  claim 1 , wherein the metal pattern includes the same material as the source and drain electrodes. 
   
   
       3 . The thin film transistor of  claim 1 , wherein the source and drain electrodes and the metal pattern include at least one of molybdenum, chromium, tungsten, molybdenum-tungsten, aluminum, aluminum-neodymium, titanium, titanium nitride, copper, a molybdenum alloy, an aluminum alloy, and a copper alloy. 
   
   
       4 . The thin film transistor of  claim 1 , further comprising an impurity-doped silicon layer between the semiconductor layer and the source and drain electrodes. 
   
   
       5 . The thin film transistor of  claim 1 , wherein the semiconductor layer is a polysilicon layer. 
   
   
       6 . The thin film transistor of  claim 1 , wherein the gate interconnection is in direct contact with the metal pattern. 
   
   
       7 . A method of manufacturing a thin film transistor, the method comprising:
 providing a substrate having a pixel portion and a peripheral portion;   forming a buffer layer on the substrate;   forming a gate electrode and a gate interconnection on the buffer layer, the gate electrode being located at the pixel portion, the gate interconnection being located at the peripheral portion;   forming a gate insulating layer on the gate electrode and the gate interconnection;   forming an amorphous semiconductor layer and patterning the amorphous semiconductor layer to form a semiconductor layer pattern on the gate electrode of the pixel portion;   forming a metal layer on the substrate to be electrically connected to the semiconductor layer pattern and the gate interconnection;   applying an electric field to the metal layer to crystallize the semiconductor layer pattern to form a semiconductor layer; and   patterning the metal layer to form source and drain electrodes electrically connected to the semiconductor layer of the pixel portion and a metal pattern on the gate interconnection.   
   
   
       8 . The method of  claim 7 , wherein the metal pattern is in direct contact with the gate interconnection. 
   
   
       9 . The method of  claim 7 , wherein the crystallization is performed by applying the electric field of about 100 V/cm 2  to about 10,000 V/cm 2  to the source/drain electrode metal layer. 
   
   
       10 . The method of  claim 7 , wherein the metal layer is formed on the substrate to a thickness of about 50 nm to about 200 nm. 
   
   
       11 . The method of  claim 7 , wherein the metal layer includes at least one of molybdenum, chromium, tungsten, molybdenum-tungsten, aluminum, aluminum-neodymium, titanium, titanium nitride, copper, a molybdenum alloy, an aluminum alloy, and a copper alloy. 
   
   
       12 . The method of  claim 7 , further comprising forming an impurity-doped silicon layer between the semiconductor layer and the source and drain electrodes. 
   
   
       13 . An organic light emitting diode display device comprising:
 organic light emitting diodes configured to emit light; and   thin film transistors coupled to the organic light emitting diodes, each thin film transistor including:
 a substrate having a pixel portion and an interconnection portion; 
 a buffer layer on the substrate; 
 a gate electrode and a gate interconnection on the buffer layer, 
   wherein the gate electrode is located at the pixel portion and a gate interconnection is located at the interconnection portion;
 a gate insulating layer on the entire substrate; 
 a semiconductor layer on the gate electrode; 
 source and drain electrodes electrically connected to the semiconductor layer; 
 an insulating layer on the entire substrate; 
 a first electrode, the source and drain electrodes, an organic layer and a second layer on the insulating layer, wherein the first electrode is electrically connected to the source and drain electrodes, an organic layer and a second layer, and 
 a metal pattern on the gate interconnection. 
   
   
   
       14 . The organic light emitting diode display device of  claim 13 , wherein the metal pattern includes the same material as the source and drain electrodes. 
   
   
       15 . The organic light emitting diode display device of  claim 13 , further comprising an impurity-doped silicon layer disposed between the semiconductor layer and the source and drain electrodes. 
   
   
       16 . The organic light emitting diode display device of  claim 13 , wherein the source and drain electrodes and the metal pattern include at least one of molybdenum, chromium, tungsten, molybdenum-tungsten, aluminum, aluminum-neodymium, titanium, titanium nitride, copper, a molybdenum alloy, an aluminum alloy, and a copper alloy. 
   
   
       17 . The organic light emitting diode display device of  claim 13 , wherein the semiconductor layer is a polysilicon layer. 
   
   
       18 . The organic light emitting diode display device of  claim 13 , wherein the gate interconnection is in direct contact with the metal pattern.