This work is addressed to investigate thermal stability of a thin TiSi film, that is its ability to resist degradation due to 2 heat treatments at high temperatures. The study was carried out as a function of the formation RT treatment (675-7508C) at the end of a common process flow. Sheet resistance measurements were employed in order to evaluate this degradation. Electrical measures were performed on large and narrow poly-Si lines, on Van Der Pauw structures and on doped mono-Si substrates. An increase in sheet resistance value of an order of magnitude for silicide formed at temperatures below 7008C with respect to the one formed at temperatures above 7008C was found, particularly on poly-Si lines. The effect is detectable independently of the structure: it was observed also on 0.75-mm wide poly-Si lines, increasing when line width decreases. Different morphological analyses were carried out for investigating the influence of the formation temperature. We explain the increase of the final sheet resistance decreasing the formation temperature as a lower thermal stability of the TiSi film, 2 leading to a thermal grooving of the silicide grains.