GeTe Liner Stressor Featuring Phase-Change- Induced Volume Contraction for Strain Engineering of Sub-50-nm p-Channel FinFETs: Simulation and Electrical Characterization

We report the experimental demonstration of strained p-channel FinFETs featuring a GeTe liner stressor that exhibits very large volume contraction (~10%) during phase change. Conformally grown GeTe liner was formed on FinFETs with sub-50-nm gate length L_G. When the GeTe liner changes phase from amorphous (α-GeTe) to polycrystalline (c-GeTe) state, it contracts and imparts very high compressive channel stress. A finite element method simulation was performed to study the channel stress in FinFETs, followed by a k · p calculation of Si valence band structure with the simulated strain tensors. The effective mass of the topmost valence band is reduced and the band dispersion between heavy-hole and light-hole sub-bands at Γ point increases with the effect of the strain induced by the GeTe liner. Significant drive current I_Dsat enhancement of 96% was observed for FinFETs with 50-nm c-GeTe liner stressor over the control devices. I_Dsat enhancement increases as L_G reduces, showing good scalability of the GeTe liner stressor for possible application in future technology nodes.