SEMICONDUCTOR FILM COMPRISING AN OXIDE CONTAINING IN ATOMS, Sn ATOMS AND Zn ATOMS

Abstract

A field effect transistor including: a substrate, and at least gate electrode, a gate insulating film, a semiconductor layer, a protective layer for the semiconductor layer, a source electrode and a drain electrode provided on the substrate, wherein the source electrode and the drain electrode are connected with the semiconductor layer therebetween, the gate insulating film is between the gate electrode and the semiconductor layer, the protective layer is on at least one surface of the semiconductor layer, the semiconductor layer includes an oxide containing In atoms, Sn atoms and Zn atoms, the atomic composition ratio of Zn/(In+Sn+Zn) is 25 atom % or more and 75 atom % or less, and the atomic composition ratio of Sn/(In+Sn+Zn) is less than 50 atom %.

1 - 8 . (canceled) 
     
     
         9 . A sputtering target that is entirely continuous for forming a semiconductor layer of a field effect transistor, comprising an oxide containing In atoms, Sn atoms and Zn atoms,
 the atomic composition ratio of Zn/(In+Sn+Zn) being 25 atom % or more and 70 atom % or less, and   the atomic composition ratio of Sn/(In+Sn+Zn) being less than 50 atom %.   
     
     
         10 - 15 . (canceled) 
     
     
         16 . The sputtering target for forming a semiconductor layer of a field effect transistor according to  claim 9 ,
 wherein the atomic composition ratio of Zn/(In+Sn+Zn) is 60 atom % or more and 67 atom % or less,   the atomic composition ratio of In/(In+Sn+Zn) is 18 atom % or more and 28 atom % or less, and   the atomic composition ratio of Sn/(In+Sn+Zn) being 5 atom % or more and less than 15 atom %.   
     
     
         17 . The sputtering target for forming a semiconductor layer of a field effect transistor according to  claim 9 ,
 wherein a Na content in the target is less than 100 ppm.   
     
     
         18 . The sputtering target for forming a semiconductor layer of a field effect transistor according to  claim 9 ,
 wherein a relative density of the target is 95% or more of a theoretical density of the target.   
     
     
         19 . The sputtering target for forming a semiconductor layer of a field effect transistor according to  claim 9 ,
 wherein a bulk resistance of the target is 20mΩcm or less.   
     
     
         20 . The sputtering target for forming a semiconductor layer of a field effect transistor according to  claim 9 ,
 wherein a transverse rupture strength of the target is 8 kg/mm 2  or more.   
     
     
         21 . The sputtering target for forming a semiconductor layer of a field effect transistor according to  claim 9 ,
 wherein a surface roughness Ra of the target is 0.5 μm or less.   
     
     
         22 . The sputtering target for forming a semiconductor layer of a field effect transistor according to  claim 9 ,
 wherein a number of pinholes in the target with a Feret's diameter of 2 μm or more is 50/mm 2 or less.