Method of Fabricating IGZO by Sputtering in Oxidizing Gas

Abstract

In some embodiments, oxidants such as ozone (O 3 ) and/or nitrous oxide (N 2 O) are used during the reactive sputtering of metal-based semiconductor layers used in TFT devices. The O 3 and N 2 O gases are stronger oxidants and result in a decrease in the concentration of oxygen vacancies within the metal-based semiconductor layer. The decrease in the concentration of oxygen vacancies may result in improved stability under conditions of negative bias illumination stress (NBIS).

What is claimed: 
     
         1 . A method comprising:
 providing a substrate;   forming a metal-based semiconductor layer above a surface of the substrate, wherein the metal-based semiconductor layer is formed using a physical vapor deposition (sputtering) process, and   wherein a sputtering atmosphere during the forming comprises at least one of ozone or nitrous oxide.   
     
     
         2 . The method of  claim 1 , wherein the metal-based semiconductor layer comprises indium, gallium, zinc, and oxygen. 
     
     
         3 . The method of  claim 1 , wherein the metal-based semiconductor layer is operable as a semiconductor layer in a thin film transistor device. 
     
     
         4 . The method of  claim 3 , wherein the thin film transistor device is operable as a transistor in a display device. 
     
     
         5 . The method of  claim 1 , wherein a temperature setpoint of a substrate holder during the forming is between room temperature and 500 C. 
     
     
         6 . The method of  claim 1 , wherein a concentration of the at least one of ozone or nitrous oxide is between 1 to 100 volume % of the sputtering atmosphere. 
     
     
         7 . The method of  claim 1 , wherein a pressure of the sputtering atmosphere is between 1 and 20 millitorr. 
     
     
         8 . The method of  claim 1 , wherein a sputtering target with a composition of In x Ga y Zn z O 4  is used for forming the metal-based semiconductor layer, wherein x:y:z is about 1:1:1. 
     
     
         9 . The method of  claim 1 , wherein a plurality of sputtering targets with compositions of In a O b , Ga c O d , and Zn e O f  are used to co-sputter the IGZO layer during the forming of the metal-based semiconductor layer. 
     
     
         10 . The method of  claim 1 , wherein the sputtering atmosphere further comprises one or more of argon, oxygen, or nitrogen. 
     
     
         11 . A thin film transistor device comprising:
 a metal-based semiconductor layer,   wherein the metal-based semiconductor layer is formed using a physical vapor deposition (sputtering) process, and   wherein a sputtering atmosphere during the forming comprises at least one of ozone or nitrous oxide.   
     
     
         12 . The thin film transistor device of  claim 11 , wherein the metal-based semiconductor layer comprises indium, gallium, zinc, and oxygen. 
     
     
         13 . The thin film transistor device of  claim 11 , wherein the metal-based semiconductor layer is operable as a semiconductor layer in a thin film transistor device. 
     
     
         14 . The thin film transistor device of  claim 13 , wherein the thin film transistor device is operable as a transistor in a display device. 
     
     
         15 . The thin film transistor device of  claim 11 , wherein a temperature setpoint of a substrate holder during the forming is between room temperature and 500 C. 
     
     
         16 . The thin film transistor device of  claim 11 , wherein a concentration of the at least one of ozone or nitrous oxide is between 1 to 100 volume % of the sputtering atmosphere during the physical vapor deposition (sputtering) process. 
     
     
         17 . The thin film transistor device of  claim 11 , wherein a pressure of the sputtering atmosphere is between 1 and 20 millitorr during the physical vapor deposition (sputtering) process. 
     
     
         18 . The thin film transistor device of  claim 11 , wherein a sputtering target with a composition of In x Ga y Zn z O 4  is used for the forming of the metal-based semiconductor layer during the physical vapor deposition (sputtering) process, wherein x:y:z is about 1:1:1. 
     
     
         19 . The thin film transistor device of  claim 11 , wherein a plurality of sputtering targets with compositions of In a O b , Ga c O d , and Zn e O f  are used to co-sputter the IGZO layer during the forming of the metal-based semiconductor layer during the physical vapor deposition (sputtering) process. 
     
     
         20 . The thin film transistor device of  claim 11 , wherein the sputtering atmosphere further comprises one or more of argon, oxygen, or nitrogen during the physical vapor deposition (sputtering) process.