SELF-ALIGNED SILICIDE PROCESS IN FORMING SEMICONDUCTOR SIDEWALLS

摘要

Salicidation of conductive levels in DRAM semiconductor devices is described. A poly I pattern is established, along with source drain implants. Oxide (25) is established along poly sidewalls in a manner which permits sidewall isolation. An isolating nitride (27) is formed, followed by a poly II pattern covered with another isolating nitride (37). An exposed sidewall of the poly II is oxidized to form oxide pattern (41). A refractory metal, such as titanium, is sputtered onto the top surface of the wafer and is sintered in a nitrogen atmosphere. TiSi2 is formed where the titanium is exposed to elemental silicon, while oxide patterns result in the titanium reacting only with the nitrogen. The titanium nitride and any unreacted titanium may then be selectively etched, leaving a desired pattern of TiSi2.