Transparent oxide semiconductor thin film transistors

Abstract

This invention relates to novel, transparent oxide semiconductor thin film transistors (TFT's) and a process for making them.

1 . A process for depositing undoped transparent oxide semiconductors, selected from the group consisting of zinc oxide, indium oxide, tin oxide, and cadmium oxide, in a field effect transistor, comprising a method selected from the group consisting of: 
 a) physical vapor deposition of undoped TOS in an effective partial pressure of oxygen mixed with an inert gas;    b) resistive evaporation of undoped TOS in an effective partial pressure of oxygen;    c) laser evaporation of undoped TOS in an effective partial pressure of oxygen;    d) electron beam evaporation of undoped T-OS in an effective partial pressure of oxygen; and    e) chemical vapor deposition of undoped T-OS in an effective partial pressure of oxygen.    
   
   
       2 . The process of  claim 1  where the physical vapor deposition is rf magnetron sputtering.  
   
   
       3 . The process of  claim 1  where the physical vapor deposition is dc magnetron sputtering:  
   
   
       4 . The process of  claim 1  where the physical vapor deposition is diode sputtering.  
   
   
       5 . The process of  claim 1  where the physical vapor deposition is triode sputtering.  
   
   
       6 . The process of  claim 1  where the physical vapor deposition is ion beam sputtering.  
   
   
       7 . The process of any of claims  1 (a),  2 ,  3 ,  4 ,  5  or  6  wherein deposition is by physical vapor deposition and wherein the inert gas is selected from the group consisting of helium, neon, argon, krypton, and xenon.  
   
   
       8 . The process of claim  1 (e) wherein the chemical vapor deposition is low pressure chemical vapor deposition.  
   
   
       9 . The process of claim  1 (e) wherein the chemical vapor deposition is plasma-enhanced chemical vapor deposition.  
   
   
       10 . The process of claim  1 (e) wherein the chemical vapor deposition is laser-enhanced chemical vapor deposition.  
   
   
       11 . The process of claim  1 (e) where the chemical vapor deposition is atomic layer chemical vapor deposition.  
   
   
       12 . The process of any one of  claims 1  to  11  wherein the effective partial pressure of oxygen is between 0.1 and 10 times the critical pressure.  
   
   
       13 . The process of any one of  claims 1  to  11  wherein the effective partial pressure of oxygen is between 0.5 and 2 times the critical pressure.  
   
   
       14 . (canceled)  
   
   
       15 . A transistor comprising a transparent oxide semiconductor made by a process of any of  claim 1 ,  2 ,  3 ,  4 ,  5 ,  6 ,  7 ,  8 ,  9 ,  10 ,  11 ,  12  or  13 .  
   
   
       16 - 25 . (canceled)