Ultra low p-type SiGe contact resistance FinFETs with Ti silicide liner using cryogenic contact implantation amorphization and Solid-Phase Epitaxial Regrowth (SPER)

Abstract

We report significant improvement of the TiSi / p-SiGe contact resistance by using a cryogenic (cold) boron implantation technique inside the contact trench of FinFET devices, providing both a source of dopants and a localized amorphization of the source/drain, self-aligned on the contact trench. A record low p-type contact resistivity of 5.9×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−9</sup> ohm-cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> is demonstrated and a 7.5% performance improvement is achieved. The variation of the implant temperature demonstrates a further improvement of the contact resistance when going to cryogenic (cold) implantation (−100 °C). Using TCAD, we demonstrate that the reduced implant temperature provides a higher degree of amorphization and reduces defects. This is the key to provide an enhanced recrystallization of the doped amorphized region through Solid Phase Epitaxial Regrowth (SPER) low temperature activation. We propose in this paper a novel mechanism for p-type contacts, and demonstrate it for the first time on state-of-the-art FinFET p-type devices using cryogenic (cold) implants and SPER regrowth.