Nitriding method of gate oxide film

Abstract

A substrate processing method comprises the step of forming an oxide film on a silicon substrate surface, and introducing nitrogen atoms into the oxide film by exposing the oxide film to nitrogen radicals excited in plasma formed by a microwave introduced via a planar antenna.

1 - 15 . (canceled) 
     
     
         16 . A method for nitriding an oxide film, comprising the steps of:
 forming an oxide film on a substrate;   forming plasma of a mixed gas of a rare gas and a nitriding gas over said oxide film; and   nitriding a surface of said oxide film by said plasma,   said nitriding step being conducted by said plasma formed under a pressure of 60 Pa or more, said nitriding step thereby converting said oxide film into an oxynitride film.   
     
     
         17 . The method as claimed in  claim 16 , wherein said step of forming said oxide film is conducted by any of a thermal annealing process of said substrate or oxidation of said substrate by plasma containing oxygen. 
     
     
         18 . The method as claimed in  claim 16 , wherein said oxide film has a thickness of 1 nm or more. 
     
     
         19 . The method as claimed in  claim 16 , wherein said step of nitriding said oxide film is conducted at a process temperature of 550° C. or less. 
     
     
         20 . A method for nitriding an oxide film, comprising the steps of:
 forming an oxide film on a substrate;   forming plasma of a mixed gas of a rare gas and a nitriding gas on said oxide film; and   nitriding a surface of said oxide film by said plasma, said nitriding step being conducted by said plasma formed under a pressure of 60-130 Pa, said nitriding step thereby converting said oxide film into an oxynitride film.   
     
     
         21 . The method as claimed in  claim 20 , wherein said step of forming said oxide film is conducted by a thermal annealing process of said substrate or oxidation of said substrate by plasma containing oxygen. 
     
     
         22 . The method as claimed in  claim 20 , wherein said rare gas is any of a Kr gas or an Ar gas. 
     
     
         23 . The method as claimed in  claim 20 , wherein said step of nitriding said oxide film is conducted at a process temperature of 550° C. or less. 
     
     
         24 . The method as claimed in  claim 20 , wherein said nitrogen concentration is controlled such that no nitrogen is detected at said interface. 
     
     
         25 . A method for nitriding an oxide film, comprising the steps of:
 providing a substrate carrying thereon an oxide film;   forming plasma of a mixed gas of a rare gas and a nitriding gas on said oxide film; and   nitriding a surface of said oxide film by said plasma, said nitriding step being conducted by said plasma formed under a pressure of 60 Pa or less, said nitriding step thereby converting said oxide film into an oxynitride film.   
     
     
         26 . The method as claimed in  claim 25 , wherein said oxide film is an oxide film formed by a thermal annealing process of said substrate or oxidation of said substrate by plasma containing oxygen. 
     
     
         27 . The method as claimed in  claim 25 , wherein said oxide film has a thickness of 1 nm or more. 
     
     
         28 . The method as claimed in  claim 25 , wherein said nitriding step is conducted with controlled nitrogen concentration such that there is formed a peak of nitrogen concentration in said oxynitride film below a top surface of said oxide film but above an interface of said oxide film and said substrate. 
     
     
         29 . A method for nitriding an oxide film, comprising the steps of:
 providing a substrate carrying thereon an oxide film;   forming plasma of a mixed gas of a rare gas and a nitriding gas on said oxide film; and   nitriding a surface of said oxide film by said plasma,   said nitriding step being conducted by said plasma formed under a pressure of 60-130 Pa, said nitriding step thereby converting said oxide film into an oxynitride film.   
     
     
         30 . The method as claimed in  claim 29 , wherein said oxide film is an oxide film formed by a thermal annealing process of said substrate or oxidation of said substrate by plasma containing oxygen. 
     
     
         31 . The method as claimed in  claim 29 , wherein said oxide film has a thickness of 1 nm or less. 
     
     
         32 . The method as claimed in  claim 29 , wherein said step of nitriding said oxide film is conducted at a process temperature of 550° C. or less.