Prospects of Hf-based Gate Dielectrics by PVD with FUSI Gate for LSTP Application

摘要

Study of Hf-based high-k gate stack prepared by PVD-Hf02 and its silicate with Ni-Fully Silicide(FUSI) gate focusing on interfacial reaction between high-k and Ni-FUSI electrode is overviewed. Effects of SiN capping between Ni-FUSI gate and high-k dielectric and post deposition anneal (PDA) to suppress the reaction during FUSI process were investigated. The SiN cap could increase transistor yield and PDA could suppress instability of the drive current due to defects/roughness caused by interfacial reaction during NiSi formation. It is noteworthy that not only elimination of poly-Si depletion but also EOT reduction was observed by replacing the poly-Si with the Ni-FUSI, which was remarkable for Ni-FUSI/SiON than Hf02 case. Hereof, by optimizing the PDA condition with SiN cap, decent electrical characteristics were obtained, lon(n/p) > 600/200 uA/um at bff = 20 pA/um at Vad = 1.1 V. This drivability meets low stand-by power specification of the MOSFET for 45 nm node.