The effects of nickel germanosilicide contacts on the biaxial compressive stress in thin epitaxial silicon-germanium alloys on silicon

摘要

When a thin Si_(1-x)Ge_x epitaxial layer is grown on Si, it is under biaxial compression. In this letter, it is shown that a nickel germanosilicide (NiSi_(1-x)Ge_x layer formed on Si_(1-x)Ge_x can significantly reduce the in-plane compressive strain in Si_(1-x)Ge_x. It is proposed that the observed reduction is due to the biaxial tensile stress applied by the NiSi_(1-x)Ge_x layer. Because the Si_(1-x)Ge_x bandgap is a strong function of the strain, this is expected to have a strong impact on the metal-semiconductor barrier height and the contact resistivity of the interface if the metal Fermi level is pinned near the Si_(1-x)Ge_x midgap.