Semiconductor device and LTPS-TFT within and method of making the same

Abstract

A thin film transistor (TFT) formed on a substrate includes a polycrystalline film, a gate insulator, a hydrogen-supplying film and a gate electrode. The polycrystalline film is formed on the substrate. Two sides of the polycrystalline film serve as the source and the drain of the semiconductor device, and the central region of the polycrystalline layer serves as the channel. The gate insulator is formed on the polycrystalline film, and the hydrogen-supplying film is formed on the gate insulator. The gate electrode is formed on the hydrogen-supplying film above the channel. The hydrogen-supplying film supplies hydrogen to the polycrystalline film, especially to the channel, so as to transform the unsaturated bonds into hydrogen bonds in the channel for avoiding the unsaturated bonds to degrade the charge carrier efficiency of the channel.

1 . A thin film transistor, comprising: 
 a substrate;    a polycrystalline film, formed on the substrate, having a source, a drain and a channel formed therebetween, the source and the drain being formed respectively on both sides of the polycrystalline;    a gate insulator formed on the polycrystalline film;    a hydrogen-supplying film formed on the gate insulator; and    a gate electrode, formed on the upper surface of the hydrogen-supplying film, over the channel of the thin film transistor.    
   
   
       2 . The thin film transistor of  claim 1 , wherein the thickness of the hydrogen-supplying film is between about 100 Å and 600 Å.  
   
   
       3 . The thin film transistor of  claim 2 , wherein the total thickness of the gate insulator and the hydrogen-supplying film is between about 800 Å and 1600 Å.  
   
   
       4 . The thin film transistor of  claim 1 , wherein said hydrogen-supplying film includes tetraethyl-orthosilicate (TEOS).  
   
   
       5 . The thin film transistor of  claim 1 , wherein said gate insulator includes tetraethyl-orthosilicate (TEOS).  
   
   
       6 . A semiconductor device comprising: 
 a substrate;    a polycrystalline film, formed on the substrate, having a source, a drain and of a channel formed therebetween, the source and the drain being formed respectively on both sides of the polycrystalline;    a gate insulator formed on the polycrystalline film;    a hydrogen-supplying film formed on the gate insulator;    a gate electrode, formed on an upper surface of the hydrogen-supplying film, over the channel of the thin film transistor;    an inner dielectric layer covering the gate electrode and the hydrogen-supplying film;    two wires passing through the inner dielectric layer to contact therebelow with the source and the drain of the polycrystalline film, respectively; and    a passivation layer covering the inner dielectric layer.    
   
   
       7 . The semiconductor device of  claim 6 , wherein the thickness of the hydrogen-supplying film is between about 100 Å and 600 Å.  
   
   
       8 . The semiconductor device of  claim 7 , wherein the total thickness of the gate insulator and the hydrogen-supplying film is between about 800 Å and 1600 Å.  
   
   
       9 . The semiconductor device of  claim 6 , wherein said hydrogen-supplying film includes tetraethyl-orthosilicate (TEOS).  
   
   
       10 . The semiconductor device of  claim 6 , wherein said gate insulator includes tetraethyl-orthosilicate (TEOS).  
   
   
       11 . The semiconductor device of  claim 6 , wherein said passivation layer includes hydrogen atoms.  
   
   
       12 . A method of manufacturing a semiconductor device, comprising: 
 forming a polycrystalline film on a substrate;    forming a gate insulator on the polycrystalline film;    forming a source and a drain in both sides of the polycrystalline film and a channel therebetween;    forming a hydrogen-supplying film on the gate insulator;    forming a gate electrode on the hydrogen-supplying film;    forming an inner layer dielectric to cover the gate electrode and the hydrogen-supplying film;    performing an annealing process to diffuse hydrogen atoms from the hydrogen-supplying film to the channel so as to transform unsaturated bonds into hydrogen bonds in the polycrystalline film; and    forming two wires to extend through the inner dielectric layer so as to contact with the source and the drain, respectively.    
   
   
       13 . The method of  claim 12 , further including forming a passivation layer to cover the inner dielectric layer.  
   
   
       14 . The method of  claim 12 , wherein the step of forming a source and a drain in both sides of the polycrystalline film and a channel therebetween comprises performing an ion implantation process to define a source and a drain in both sides of the polycrystalline film and a channel therebetween.  
   
   
       15 . The method of  claim 12 , wherein said ion implantation process includes an ion activation process to activate ions in the source and the drain.  
   
   
       16 . The method of  claim 12 , wherein said hydrogen-supplying film includes tetraethyl-orthosilicate (TEOS).  
   
   
       17 . The method of  claim 12 , wherein said gate insulator includes tetraethyl-orthosilicate (TEOS).  
   
   
       18 . The method of  claim 12 , wherein the temperature of said annealing process is between about 300° and 420° C.  
   
   
       19 . The method of  claim 12 , wherein the time period of said annealing process is between about 20 min and 60 min.  
   
   
       20 . The method of  claim 12 , wherein said gate insulator is a multi-layer structure of tetraethyl-orthosilicate (TEOS).