Dual Work Function Phase Controlled Ni-FUSI CMOS (NiSi NMOS, Ni2Si or Ni31Si12 PMOS): Manufacturability, Reliability & Process Window Improvement by Sacrificial SiGe Cap

This work presents the first comprehensive evaluation of the manufacturability and reliability of dual WF phase controlled Ni-FUSI/HfSiON CMOS (NMOS: NiSi; PMOS: Ni₂Si and Ni₃₁ Si₁₂ evaluated) for the 45 nm node. RTP1 and poly/spacer height were identified as the most critical process control parameters in our flow. We demonstrate that a novel sacrificial SiGe cap addition to the flow (improved poly-Si/spacer height control) opens the RTP1 process window from ~5degC to ~20degC for gate lengths down to 45nm, making scalable dual WF CMOS Ni-FUSI manufacturable. We demonstrate Vt control with sigma~19mV (including wafer to wafer variation, N=1000, 45 nm devices) for NMOS (NiSi), and sigma~21mV for PMOS. TDDB and NBTI reliability evaluation of NiSi and, for the first time, of Ni₂Si and Ni₃₁Si₁₂ was done. ~1V or larger operating voltages (V_op) were extrapolated for a 10 years lifetime. Using a higher back-end thermal budget showed no reliability degradation