The formation of CoSi2 and TiSi2 on poly-Si lines, with nominal dimensions ranging from 0.5-mu-m to 1.01-mu-m, 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 CoSi2-polycide lines compared to TiSi2 lines. Cross-sectional TEM and SEM investigations showed that the silicide/poly-Si interface was severely bowed for both CoSi2 and TiSi2. A parallel bowing of the silicide surface occurred on the TiSi2 lines, while the surface of the CoSi2 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 CoSi2 and TiSi2-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 linewidth loss seen on CoSi2 lines.