Titanium silicide/titanium nitride full metal gates for dual-channel gate-first CMOS

Abstract

We demonstrate a thermally stable titanium silicide/titanium nitride (TiSix/TiN) full metal gate (FMG) for dual-channel gate-first high-k/metal gate complementary metal-oxide-semiconductor technology. Unlike prior tungsten-based FMG, the simple TiSix/TiN gate electrode does not require any additional barrier layer preventing oxygen down-diffusion during high-temperature processing, as the TiSix itself blocks oxygen. With HfO2-based gate dielectrics and without any oxygen scavenging scheme, we thus demonstrate a capacitance-equivalent thickness in inversion (Tinv of 1.11 nm, corresponding to an equivalent oxide thickness of ∼ 0.7nm. Silicon channel nFET and silicon germanium channel pFET parametrics are similar to those of control devices utilizing a conventional a-Si/TiN metal-inserted poly-Si stack (MIPS) gate, while providing superior gate sheet resistance. By supplanting MIPS with such an FMG, we anticipate that contacted gate pitch can be scaled aggressively via reduced gate height and borderless source/drain contacts.