Oxidizing method and oxidation system

Abstract

An oxidation method of oxidizing surfaces of workpieces heated at a predetermined temperature in a vacuum atmosphere in a processing vessel produces active hydroxyl and active oxygen species. The active hydroxyl and active oxygen species oxidize the surfaces of the workpieces in a processing vessel. Both the intrafilm thickness uniformity and the characteristics of the oxide film can be improved, maintaining oxidation rate on a relatively high level.

What is claimed is:  
     
         1 . An oxidation method of oxidizing surfaces of workpieces heated at a predetermined temperature in a vacuum atmosphere within a processing vessel, said oxidation method comprising the steps of: 
 producing active hydroxyl and active oxygen species; and    oxidizing the surfaces of the workpieces by the active hydroxyl and the active oxygen species.    
     
     
         2 . The oxidation method according to  claim 1 , wherein 
 an oxidative gas and a reductive gas are supplied into the processing vessel by separate gas supply systems, respectively, in the step of producing active hydroxyl and active oxygen species.    
     
     
         3 . The oxidation method according to  claim 1  or  2 , wherein 
 the processing vessel has a predetermined length, the workpieces are arrange at predetermined pitches in a processing region in the processing vessel,  
 an oxidative gas and a reductive gas are supplied into the processing vessel so as to flow from one of opposite ends of the processing vessel toward the other of opposite ends in the step of producing active hydroxyl and active oxygen species.  
 
     
     
         4 . The oxidation method according to  claim 3 , wherein 
 parts of the processing vessel through which the oxidative gas and the reductive gas are supplied into the processing vessel are positioned a predetermined distance apart from the processing region of the workpieces in the processing vessel.    
     
     
         5 . The oxidation method according to  claim 4 , wherein 
 the predetermined distance is determined such that the oxidative gas and the reductive gas do not affect adversely temperature distribution in the processing region of the workpieces and the oxidative gas and the reductive gas supplied into the processing vessel can be satisfactorily mixed.    
     
     
         6 . The oxidation method according to  claim 5 , wherein 
 the predetermined distance is about 100 mm or above.    
     
     
         7 . The oxidation method according to  claim 1 , wherein 
 the oxidative gas contains one or some of O 2 , N 2 O, NO and NO 2 , and the reductive gas contains one or some of H 2 , NH 3 , CH 4  and HCl.    
     
     
         8 . The oxidation method according to  claim 1 , wherein the pressure of the vacuum atmosphere is below 133 Pa (1 Torr).  
     
     
         9 . The oxidation method according to  claim 8 , wherein 
 the pressure of the vacuum atmosphere is in the range of 6.7 to 67 Pa (0.05 to 0.5 Torr).    
     
     
         10 . The oxidation method according to  claim 1 , wherein 
 the predetermined temperature is in the range of 400 to 1100° C.    
     
     
         11 . The oxidation method according to  claim 3 , wherein 
 an additional oxidative gas and an additional reductive gas are supplied additionally into the processing vessel so as to flow from in an opposite direction of the oxidative gas and the reductive gas flowing from one end toward the other end in the step of producing active hydroxyl and active oxygen species.    
     
     
         12 . An oxidation system comprising: 
 a processing vessel for containing workpieces;    a support means for supporting workpieces in a processing region in the processing vessel;    a heating means for heating workpieces;    an evacuation system for evacuating the processing vessel;    an oxidative gas supply system for supplying an oxidative gas into the processing vessel; and    a reductive gas supply system separate from the oxidative gas supply system, for supplying a reductive gas into the processing vessel to produce active hydroxyl and active oxygen species by the interaction of the oxidative gas and the reductive gas;    wherein surfaces of workpieces placed in the processing region are oxidized by the active hydroxyl and the active oxygen species.    
     
     
         13 . The oxidation system according to  claim 12 , wherein 
 the oxidative gas supply system and the reductive gas supply system are connected to one end of the processing vessel to make the oxidative gas and the reductive gas flow toward the other end of the processing vessel.    
     
     
         14 . The oxidation system according to  claim 13 , wherein 
 the heating means heats both the oxidative gas and the reductive gas.    
     
     
         15 . The oxidation system according to  claim 13  or  14 , wherein 
 the oxidative gas supply system has an oxidative gas supply nozzle, the reductive gas supply system has a reductive gas supply nozzle, the oxidative gas supply nozzle and the reductive gas supply nozzle have outlets positioned a predetermined distance apart from the processing region of the workpieces in the processing vessel.  
 
     
     
         16 . The oxidation system according to  claim 15 , wherein 
 the predetermined distance is determined such that the oxidative gas and the reductive gas do not affect adversely temperature distribution in the processing region of the workpieces and the oxidative gas and the reductive gas can be satisfactorily mixed.    
     
     
         17 . The oxidation system according to  claim 16 , wherein 
 the predetermined distance is about 100 mm or above.    
     
     
         18 . The oxidation system according to  claim 12 , wherein 
 the oxidative gas supply system has an oxidative gas supply nozzle, the reductive gas supply system has a reductive gas supply nozzle, both the nozzles extend from one end of the processing vessel toward the other end of the processing vessel and have gas outlets positioned at the other end of the processing vessel.    
     
     
         19 . The oxidation system according to  claim 12 , wherein 
 the oxidative gas contains one or some of O 2 , N 2 O, NO and NO 2 , and the reductive gas contains one or some of H 2 , NH 3 , CH 4  and HCl.    
     
     
         20 . The oxidation system according to  claim 18 , wherein 
 the oxidative gas supply system has a supplementary oxidative gas supply nozzle, the reductive gas supply system has a supplementary reductive gas supply nozzle, and the supplementary oxidative gas supply nozzle and the supplementary reductive gas supply nozzle have gas outlets disposed at one end of the processing vessel.