Method of forming junction leakage free metal silicide in a semiconductor wafer by alloying refractory metal

Abstract

A method of forming metal silicide in a semiconductor wafer with reduced junction leakage introduces an alloy at cobalt grain boundaries within a cobalt layer that overlays a silicon layer. The alloy element can be precipitated during deposition of the cobalt and the alloy element, or by an intermediate anneal after deposition. The cobalt layer and the silicon layer are then annealed to form metal silicide regions. By precipitating an alloy at the cobalt grain boundaries, cobalt diffusion at the grain boundaries is retarded during a first rapid thermal annealing step. Bulk diffusion is encouraged, and a more uniform silicide film with reduced interface roughness is produced. Since the interface roughness is reduced with the methods of the present invention, junction leakage is reduced. This allows shallower junctions to be fabricated, leading to devices with improved performance.

Dependencies are inferred from the claim text.