Window size effect on lateral growth of nickel silicide

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Abstract
Window size effect on lateral growth of nickel silicide in contact windows cut into oxide grown on Si (100) is studied. The growth rate is found to be independent of window size and follows the diffusion‐limited process with activation energy of 1.5 eV. The Si erosions are observed to grow due to predominant Si diffusion for vacuum anneal above 600 °C. This phenomenon becomes greatly pronounced with fine windows of 2 μm in diameter. We attribute this to (i) an enhanced stress level in fine windows causing reduction in the growth temperature of epitaxial NiSi2 in the windows and (ii) difference in surface energies of epitaxial NiSi2 formed and the Si substrate resulting in the shrinkage of the epitaxial NiSi2 dimension in the window. No such behavior is observed under identical conditions when Si (111) is used. We believe this is due to the fact that the lateral growth of nickel silicide in this case is about a quarter of that for Ni‐Si (100) lateral samples. Finally the technological importance of this study is pointed out.