Method for fabricating semiconductor device and semiconductor device

Abstract

Part of a first oxide film formed by thermal oxidation is removed by etching. A second oxide film is formed in the part of substrate from which the first oxide film has been removed using heated nitric acid. The two oxide films are nitrided by a nitrogen plasma having a low energy so as to be first and second gate insulating films, i.e., oxynitride films, respectively.

1 - 19 . (canceled)  
     
     
         20 . A semiconductor device comprising: 
 a semiconductor substrate;    a gate insulating film formed on the semiconductor substrate; and    a gate electrode formed on the gate insulating film,    wherein the gate insulating film contains silicon dioxide as a main component and nitrogen and has a physical thickness of not less than 0.3 nm and not more than 3 nm,    wherein the concentration of the nitrogen contained in the gate insulating film is maximum at a distance of 1 nm or less in the depth direction from a surface of the gate insulating film on which the gate electrode is formed,    wherein the maximum concentration of the nitrogen is not less than 5 atomic % and not more than 100 atomic %, and    wherein the nitrogen concentration at the interface between the semiconductor substrate and the gate insulating film is 1.5 atomic % or less.    
     
     
         21 . A semiconductor device comprising: 
 a semiconductor substrate;    a gate insulating film formed on the semiconductor substrate; and    a gate electrode formed on the gate insulating film,    wherein the electrical thickness of the gate insulating film measured by a capacitance-voltage measurement is 0.3 nm or more,    where the electrical thickness of the gate insulating film is not less than 0% and not more than 90% of the electrical thickness of a silicon dioxide film of which the physical thickness is the same as the physical thickness of the gate insulating film, and    wherein a leakage current flowing in the gate insulating film when a driving voltage of not less than 0.5 V and not more than 2 V is applied is not less than 1/10000 and not more than ⅓ of a leakage current flowing in the silicon dioxide film.    
     
     
         22 . The semiconductor device of  claim 21 , wherein the gate insulating film contains silicon dioxide as a main component and nitrogen.  
     
     
         23 . A semiconductor device comprising: 
 a semiconductor substrate;    a gate insulating film formed on the semiconductor substrate; and    a gate electrode formed on the gate insulating film,    wherein the gate insulating film contains silicon dioxide as a main component and nitrogen and has a physical thickness of not less than 0.3 nm and not more than 3 nm, and    wherein the silicon dioxide is formed using a solution containing an oxidizer.