Influence of Oxide Interlayer by TiN Metal Gate in High-k First CMOS Devices

Abstract

Due to its good film stability and electric property of high effective work function, TiN film has been widely used as high-k gate dielectric capping layer or work function metal in advanced High-k/metal gate CMOS devices. In this work, different TiN films were prepared by atomic layer deposition (ALD) and plasma vapor deposition (PVD) respectively, their thermal stability and interaction with gate stack films were investigated. Furthermore, their impacts on interface properties of interfacial oxide/high-k and interfacial oxide/silicon were also studied. The results show that both ALD and PVD TiN films have good thermal stability, while they tend to gather oxygen from atmosphere during sequential process steps. After high temperature annealing, the gathered oxygen in TiN film is easy to diffuse upward into TiN/poly-Si interface to form a thin TiSixOy layer above TiN film, and diffuse downward through high-k dielectric film resulting in interfacial oxide layer (IL) regrowth.