Formation of CoSi 2 and TiSi 2 on narrow poly-Si lines

Abstract The formation of CoSi 2 and TiSi 2 on poly-Si lines, with nominal dimensions ranging from 0.5 μm to 1.0 μm, has been studied. Side-wall spacers were formed to allow a self-aligned silicide formation (SALICIDE) process. Silicidation was obtained, in an RTP system, via a solid-solid reaction between the metal and the silicon. Electrical measurements revealed a larger apparent line-width loss, representing a higher sheet resistance, for CoSi 2 -polycide lines compared to TiSi 2 lines. Cross-sectional TEM and SEM investigations showed that the silicide/poly-Si interface was severely bowed for both CoSi 2 and TiSi 2 . A parallel bowing of the silicide surface occurred on the TiSi 2 lines, while the surface of the CoSi 2 lines remained quite flat. Moreover, similar bowing of the silicide interface is also observed after silicidation of mono-Si in narrow oxide windows. Plausible explanations for the silicide/Si interface bowing and the development of different cross-sectional geometries for CoSi 2 and TiSi 2 -polycide lines, are presented. It is suggested, that the observed difference in the cross-sectional geometry of the two silicides is responsible for the larger line-width loss seen on CoSi 2 lines.