Manufacturing enhancements for CoSi2 self-aligned silicide at the 0.12-μm CMOS technology node

As integrated circuit manufacturing moves to the 0.12-μm and finer-line technologies, a more comprehensive understanding of the manufacturability of the cobalt silicide (CoSi₂) module is needed. In this paper, a detailed study of the manufacturability of cobalt self-aligned silicide (Salicide) for the 0.12-μm and finer technology nodes is discussed. Experimental design for the CoSi₂ processing steps included cobalt (Co), titanium (Ti), and titanium nitride (TiN) depositions; the first and second rapid thermal anneals (RTA1 and RTA2) and the selective metal etch. Grain structure (by X-ray diffraction), surface roughness (by atomic force microscopy), sheet resistance, thickness uniformity and leakage current measurements were taken to characterize the SAlicide process module. The results show that by using a TiN rather than Ti capping layer: a) the CoSi₂ sheet resistance nonuniformity has been improved; b) the CoSi₂ thickness is independent of the capping layer thickness; and c) CoSi₂ to silicon interface roughness is reduced, thus reducing junction leakage currents. Anneal studies indicate the RTA1 temperature dominates the CoSi₂ grain structure and grain size with higher annealing temperatures resulting in rougher CoSi₂ surfaces and higher junction leakage currents.