Pre-doping effects on Ni fully silicided metal gate on SiO 2 dielectric

Abstract

This paper investigates the effects of ion implantation and spike activation anneal on the work function (WF) modulation of Ni fully silicided (FUSI) metal gate on SiO 2 dielectrics, and on the FUSI gated SiO 2/Si(1 0 0) interface trap properties by using high-frequency capacitance–voltage ( C– V) and photonic high-frequency C– V measurements. Undoped Ni FUSI gate has good thermal stability, and its WF before and after forming gas annealing (FGA) is 4.75 eV and 4.74 eV, respectively. As pre-doping and B pre-doping shift the flatband voltage of the Ni FUSI gated MOS capacitor negatively and positively, respectively. As-doped Ni FUSI gate may delaminate or peel off after FGA. Before FGA, a characteristic D it peak ranging from 5.7 × 10 12 to 1.2 × 10 13 cm −2 eV −1 was observed at approximately 0.63–0.74 eV above the valence band edge for As-doped and B-doped Ni FUSI gated capacitors which received a spike activation anneal after ion implantation. But such a D it peak was not observed in undoped Ni FUSI gated capacitors or those doped but without a spike activation anneal. The characteristic peak, which may be related to P b defects at the SiO 2/Si(1 0 0) interface, could be eliminated after FGA.