Influence of TiSi2 formation temperature on film thermal stability

This work is addressed to investigate thermal stability of a thin TiSi2 fil m, that is its ability to resist degradation due to heat treatments at high temperatures. The study was carried out as a function of the formation RT treatment (675-750 degrees C) at the end of a common process flow. Sheet re sistance measurements were employed in order to evaluate this degradation. Electrical measures were performed on large and narrow poly-Si lines, on Va n Der Pauw structures and on doped mono-Si substrates. An increase in sheet resistance value of an order of magnitude for silicide formed at temperatu res below 700 degrees C with respect to the one formed at temperatures abov e 700 degrees C was found, particularly on poly-Si lines. The effect is det ectable independently of the structure: it was observed also on 0.75-mu m w ide poly-Si lines, increasing when line width decreases. Different morpholo gical analyses were carried out for investigating the influence of the form ation temperature. We explain the increase of the final sheet resistance de creasing the formation temperature as a lower thermal stability of the TiSi 2 film, leading to a thermal grooving of the silicide grains. (C) 2000 Else vier Science B.V. All rights reserved.