Method for producing a target

Abstract

A target is produced inexpensively by safely incorporating an additive which is inflammable in the atmosphere. A primary alloy in a molten state is formed by adding an additive into a principal material in a low-level oxygen atmosphere, and a secondary alloy is produced by increasing the volume of the primary alloy through adding the principal material to the molten primary alloy in the atmospheric atmosphere. Since the primary alloys in the molten or solid condition are stable, it does not ignite in the atmosphere. Since the volume of the primary alloy is smaller than that of the secondary alloy, a smaller size of a vacuum chamber 11 for the formation of the first atmosphere suffices.

1 . A method for producing a target, comprising the steps of: 
 preparing a primary alloy in a molten state by adding an additive into a principal material in a first atmosphere;    adding the principal material to the primary alloy in a secondary atmosphere to obtain a secondary alloy in a molten state having a content ratio of the additive lower than that of the primary alloy; and    producing a sputtering target made of the secondary alloy,    wherein a partial pressure of oxygen in the first atmosphere is lower than a partial pressure of oxygen in the secondary atmosphere.    
     
     
         2 . The target producing method according to  claim 1 , wherein the secondary atmosphere is the atmospheric atmosphere.  
     
     
         3 . The target producing method according to  claim 2 , wherein the pressure of the first atmosphere is lower than that of the atmospheric atmosphere.  
     
     
         4 . The target producing method according to  claim 1 , wherein aluminum (Al) is used as the principal material.  
     
     
         5 . The target producing method according to  claim 1 , wherein an inflammable metal that ignites if it is melted in the atmosphere is used as the additive.  
     
     
         6 . The target producing method according to  claim 1 , wherein: 
 at least one material selected from the group consisting of Ce, Pr, Dy and Y is used as the additive, and    the additive is incorporated into the sputtering target in the range of from 0.5 atm % or more to 5 atm % or less.    
     
     
         7 . The target producing method according to  claim 1 , wherein a partial pressure of oxygen in the first atmosphere is set at a pressure of 0.2 Pa or less.  
     
     
         8 . The target producing method according to  claim 7 , wherein the first atmosphere is set at a pressure of 130 Pa or more.  
     
     
         9 . The target producing method according to  claim 1  to form the first atmosphere in a vacuum chamber and adding the additive into the principal material inside the vacuum chamber, the target producing method further comprising the steps of; 
 reducing the interior pressure of the vacuum chamber to set a pressure of 1 Pa or less, and then,    introducing an inert gas into the vacuum chamber to set the pressure of 130 Pa or more so as to form the first atmosphere.