Semiconductor device, measurement apparatus, and measurement method of relative permittivity

Abstract

The field of an oxide semiconductor has been attracted attention in recent years. Therefore, the correlation between electric characteristics of a transistor including an oxide semiconductor layer and physical properties of the oxide semiconductor layer has not been clear yet. Thus, a first object is to improve electric characteristics of the transistor by control of physical properties of the oxide semiconductor layer. A semiconductor device including at least a gate electrode, an oxide semiconductor layer, and a gate insulating layer sandwiched between the gate electrode and the oxide semiconductor layer, where the oxide semiconductor layer has the relative permittivity of equal to or higher than 13 (or equal to or higher than 14), is provided.

1 . (canceled) 
     
     
         2 . A method for measuring a relative permittivity, comprising the steps of:
 forming a measurement apparatus which comprises:
 a semiconductor; 
 an oxide semiconductor layer provided over the semiconductor, wherein the oxide semiconductor layer has a wider band gap than the semiconductor; and 
 a gate electrode provided over the oxide semiconductor; 
   calculating a capacitance Ca in an accumulation region of C-V characteristics of the measurement apparatus; and   calculating a relative permittivity c of the oxide semiconductor layer by substituting the capacitance C a  into the following formula (1),   
       
         
           
             
               
                 
                   
                     ɛ 
                     = 
                     
                       
                         C 
                         a 
                       
                        
                       
                         1 
                         
                           ɛ 
                           0 
                         
                       
                        
                       
                         d 
                         S 
                       
                     
                   
                 
                 
                   
                     ( 
                     1 
                     ) 
                   
                 
               
             
           
         
         wherein, in the formula, ∈ 0  is a vacuum permittivity, S is an area of the gate electrode, and d is a thickness of the oxide semiconductor layer. 
       
     
     
         3 . The method for measuring a relative permittivity according to  claim 2 , wherein the semiconductor is a silicon wafer. 
     
     
         4 . The method for measuring a relative permittivity according to  claim 3 , wherein the silicon wafer is n-type or p-type. 
     
     
         5 . The method for measuring a relative permittivity according to  claim 2 , wherein the oxide semiconductor layer includes indium, gallium and zinc.