Quantum-barriers and ground-plane isolation: A path for scaling bulk-FinFET technologies to the 7 nm-node and beyond

The electrostatic integrity of 7 nm-node bulk FinFETs (FF) is studied by TCAD. Lowly-doped bulk-FF have worse electrostatics than SOI- and GeOI-FF. However, by introducing a 200 meV band offset/quantum barrier (QB) under the channel or a > 1e18 doped ground-plane (GP), the electrostatics of bulk-FF match those of SOI-and GeOI-FF for the 7 nm-node. For sufficient substrate isolation, the band offset must be positioned within 5 nm of the STI edge. The QB layer that provides the offset can be thinned down to 10 nm. A GP is more robust to variations in position, but thinning this layer requires doping levels that are undesired especially for Ge. Bulk-FF with GP or QB isolation show good scalability to the 5 nm-node, improving both I_EFF and DIBL.