3D nanowire gate-all-around transistors: Specific integration and electrical features

摘要

Three level stacked Si nanowires transistors with HfO_2/TiN/poly-Si gate all around stacks (transistors called hereafter 3NWG) were processed, thanks to a self-aligned process. A current gain of 4.3 for NMOS and 4.7 for PMOS compared to planar SOI was demonstrated for V_D = 1.2 V and V_G - V_T = 0.8 V, thanks to a 3D integration scheme (stacked and aligned nanowires). Those 3NWG devices revealed a current gain of 4.9 for NMOS and 4.2 for PMOS for V_D = 50 mV when getting rid of the access resistance impact. Thanks to capacitance measurements, we found an expected inversion charge gain per plan-view surface of 6.4, highlighting the potentiality of the 3NWG device. The split-CV technique was used to extract electron and hole effective mobilities. The transport in 3NWG (on etched surfaces) was compared to the one in planar SOI devices.