Junction Leakage Due to CoSi2 Formation on As‐Doped Polysilicon

Abstract

Junction leakage has been observed for shallow diodes that simulate emitter‐base junctions in npn bipolar transistors, due to formation on As‐doped polysilicon. The leakage depends on the Co thickness, the polysilicon thickness, and the device area, but is relatively independent of the Co anneal conditions between 600 and 800°C. Severe roughness at the interface is also observed, especially after annealing at 800°C. The leakage is probably due to protrusions in the substrate that are produced during the initial silicide formation.