Silicide formation and dopant diffusion in silicon

Abstract

Recently, we reported that formation of Pd2Si from Pd induced asymmetric diffusion of buried dopant marker layers in the silicon substrate at surprisingly low temperatures (200°C) [M. Wittmer, P. Fahey, G. J. Scilla, S. S. Iyer, and M. Tejwani, Phys. Rev. Lett. 66, 632 (1991)]. We concluded that asymmetric diffusion could not be readily explained within the framework of existing diffusion theories. In this investigation we have examined in detail whether the observed asymmetries in profile shapes after silicidation could be induced by the secondary-ion mass spectroscopy (SIMS) profiling technique; however, we were unable to show that asymmetries can be attributed solely to the SIMS measurements. We have also utilized high-resolution Rutherford backscattering to confirm with another profiling technique that dopant diffusion does indeed occur as a result of the silicidation process. © 1992 The American Physical Society.