High-purity aluminum sputter targets and method of manufacture

Abstract

The high-purity aluminum sputter target is at least 99.999 weight percent aluminum and has a grain structure. The grain structure is at least 99 percent recrystallized and has a grain size of less than 125 μm. The method forms high-purity aluminum sputter targets by first cooling a high-purity target blank to a temperature of less than −50° C. and then deforming the cooled high-purity target blank introduces intense strain into the high-purity target. After deforming, recrystallizing the grains at a temperature below 200° C. forms a target blank having at least 99 percent recrystallized grains. Finally, finishing at a low temperature sufficient to maintain the fine grain size of the high-purity target blank forms a finished sputter target.

We claim:  
     
         1 . A high-purity aluminum sputter target, the sputter target being at least 99.999 weight percent aluminum and having a grain structure, the grain structure being at least about 99 percent recrystallized and having a grain size of less than about 125 μm.  
     
     
         2 . The sputter target of  claim 1  wherein the sputter target has a monoblock structure.  
     
     
         3 . The sputter target of  claim 1  wherein the sputter target has a sputter target face for sputtering the sputter target; and the sputter target face has a grain orientation ratio of at least about 35 percent (200) orientation.  
     
     
         4 . A high-purity aluminum sputter target, the sputter target being at least 99.999 weight percent aluminum and having a grain structure, the grain structure being at least about 99 percent recrystallized and having a grain size of less than about 100 μm.  
     
     
         5 . The sputter target of  claim 4  wherein the sputter target has a monoblock structure.  
     
     
         6 . The sputter target of  claim 4  wherein the sputter target has a sputter target face for sputtering the sputter target; and the sputter target face has a grain orientation ratio of at least about 35 percent (200) orientation.  
     
     
         7 . A high-purity aluminum sputter target, the sputter target being at least 99.999 weight percent aluminum and having a grain structure, the grain structure being at least about 99 percent recrystallized and having a grain size of less than about 80 μm.  
     
     
         8 . The sputter target of  claim 7  wherein the sputter target has a monoblock structure.  
     
     
         9 . The sputter target of  claim 7  wherein the sputter target has a sputter target face for sputtering the sputter target; and the sputter target face has a grain orientation ratio of at least about 40 percent (200) orientation and about 5 to 35 percent of each of the (111), (220) and (311) orientations.  
     
     
         10 . A method of forming high-purity aluminum sputter targets comprising the steps of: 
 a) cooling a high-purity target blank to a temperature of less than about −50° C., the high-purity target blank having a purity of at least 99.999 percent and grains having a grain size;    b) deforming the cooled high-purity target blank to introduce strain into the high-purity target blank and to reduce the grain size of the grains;    c) recrystallizing the grains at a temperature below about 200° C. to form a target blank having recrystallized grains, the target blank having at least about 99 percent recrystallized grains and the recrystallized grains having a fine grain size; and    d) finishing the high-purity target blank to form a finished sputter target at a low temperature sufficient to maintain the fine grain size of the finished sputter target.    
     
     
         11 . The method of  claim 10  including the additional step of upquenching the high-purity target to a temperature less than about 200° C. to stabilize the grain size of the high-purity target.  
     
     
         12 . The method of  claim 10  wherein the deforming is rolling.  
     
     
         13 . The method of  claim 12  wherein the rolling is multiple pass rolling and including the additional step of cooling the target blank between rolling passes.  
     
     
         14 . A method of forming high-purity aluminum sputter targets comprising the steps of: 
 a) cooling a high-purity target blank to a temperature of less than about −50° C., the high-purity target blank having a purity of at least 99.999 percent and grains having a grain size;    b) deforming the cooled high-purity target blank to introduce strain into the high-purity target blank and to reduce the grain size of the grains;    c) recrystallizing the grains at a temperature below about 200° C. to form a target blank having recrystallized grains, the target blank having at least about 99 percent recrystallized grains and the recrystallized grains having a fine grain size of less than about 125 μm; and    d) finishing the high-purity target blank to form a finished sputter target at a low temperature sufficient to maintain the fine grain size of the finished sputter target at less than about 125 μm.    
     
     
         15 . The method of  claim 14  including the additional step of upquenching the high-purity target to a temperature less than about 150° C. to stabilize the grain size of the high-purity target.  
     
     
         16 . The method of  claim 14  wherein the upqenching is into a liquid bath selected from the group consisting of oil, water, alcohol and mixtures thereof.  
     
     
         17 . The method of  claim 16  wherein the upquenching is into agitated water.  
     
     
         18 . The method of  claim 14  wherein the deforming is rolling.  
     
     
         19 . The method of  claim 18  wherein the rolling is multiple pass rolling and including the additional step of cooling the target blank between rolling passes.