SON (Silicon-On-Nothing) P-MOSFETs with totally silicided (CoSi₂) polysilicon on 5 nm-thick Si-films: the simplest way to integration of metal gates on thin FD channels

摘要

In this paper, the first SON (Silicon On Nothing) devices with metal gate are presented. Extremely thin fully depleted Si-films are recognized to be integrable with single-metal gate (mid-gap) due to their intrinsically low threshold voltage. In this work we present mid-gap CoSi₂ metal gate by total gate silicidation on SON transistors with Si-conduction channel thickness down to 5 nm. Due to its architecture and to the continuity between SD areas and the bulk, SON transistors allow deep silicidation processing down to the gate oxide, meaning that no more polysilicon is left. SON PMOS devices were performed with 55 nm CoSi₂ gate length with 5 nm of Si-channel thickness, and show excellent performances (350 μA/μm I_on with only 0.1 nA I_off at -1.4 V with T_ox=20 Å). The polydepletion is of course suppressed and the gate resistance (<2 Ω/□) is very competitive for RF applications.