Internal gettering by metal alloy clusters

Abstract

The present invention relates to the internal gettering of impurities in semiconductors by metal alloy clusters. In particular, intermetallic clusters are formed within silicon, such clusters containing two or more transition metal species. Such clusters have melting temperatures below that of the host material and are shown to be particularly effective in gettering impurities within the silicon and collecting them into isolated, less harmful locations. Novel compositions for some of the metal alloy clusters are also described.

1 . A material comprising crystalline silicon containing therein a plurality of metal alloy clusters, wherein said metal alloy clusters have the NiSi 2  crystal structure and wherein the individual Ni crystal sites of said metal alloy clusters may contain a Ni atom or another 3d metal. 
     
     
         2 . A material as in  claim 1  wherein said 3d metal is Fe. 
     
     
         3 . A material comprising crystalline silicon containing therein a plurality of metal alloy clusters, wherein said metal alloy clusters have the NiSi 2  crystal structure and wherein the individual Si crystal sites of said metal alloy clusters may contain a Si atom or another 3d metal. 
     
     
         4 . A material as in  claim 3  wherein said 3d metal is Cu. 
     
     
         5 . A material comprising crystalline silicon containing therein a plurality of metal alloy clusters, wherein said metal alloy clusters have the Cu 3 Si crystal structure and wherein the individual Cu crystal sites of said metal alloy clusters may contain a Cu atom or another 3d metal. 
     
     
         6 . A material as in  claim 5  wherein said 3d metal is Ni. 
     
     
         7 . A material having substantially the NiSi 2  crystal structure and a chemical composition of substantially Ni (1-x) Fe x Cu y Si (1-y)  wherein x is less than about 0.2 and y is less than about 0.18. 
     
     
         8 . A material having substantially the NiSi 2  crystal structure and a chemical composition of substantially Ni (1-x) Cu x Si 2  wherein x is less than about 0.666. 
     
     
         9 . A material having substantially the Cu 3 Si crystal structure and a chemical composition of substantially Ni x Cu (3-x) Si wherein x is less than about 0.668. 
     
     
         10 . A material having substantially the NiSi crystal structure and a chemical composition of substantially NiCu x Si (1-x)  wherein x is less than about 0.03. 
     
     
         11 . A material as in  claim 1  wherein said 3d metal is Cu.