Method of forming ultra-shallow junctions in a semiconductor wafer with silicon layer deposited from a gas precursor to reduce silicon consumption during salicidation

Abstract

A method of forming ultra-shallow junctions in a semiconductor wafer forms the gate and source/drain junctions having upper surfaces at first metal suicide regions on the gate and source/drain junctions. These first metal silicide regions have a higher resistivity. Amorphous silicon is deposited on the first metal suicide regions by plasma enhanced chemical vapor deposition (PECVD). The PECVD process may be a lower pressure deposition process, performed at multiple stations to form the amorphous silicon layer in multiple layers. This creates a more uniform amorphous silicon layer across the wafer and different patterning densities, thereby improving device performance and characteristics. Annealing is then performed to form second metal silicide regions of a lower resistivity, by diffusion reaction of the first metal silicide regions and the amorphous silicon that was deposited by the PECVD process.

Dependencies are inferred from the claim text.