Vertically stacked nanowire MOSFETs for sub-10nm nodes: Advanced topography, device, variability, and reliability simulations

Abstract

Using an advanced simulation framework we analyze a recent sub-10 nm technology demonstration based on stacked nanowire transistors (NW-FETs). The study encompasses (i) topography simulation which realistically reproduces the fabricated device, (ii) device simulation based on the subband Boltzmann transport equation (iii) a comprehensive set of scattering models for the gate stack, (iv) physical models for time-zero variability and BTI device degradation. We find that (i) the fabrication process introduces parasitic capacitances not present in a comparable FinFET, (ii) the device performance is significantly affected by interface-charge-induced Coulomb scattering resulting in up to 50% reduction in drain current compared to an ideal device, (iii) device time-zero variability is increased due to a lower amount of dopant atoms per device, (iv) the device is more affected by BTI than a comparable FinFET. Using physics-based TCAD for technology path-finding and device optimization, we are able to point out critical improvements required for the stacked NW-FET to surpass current FinFET technology.