A novel junctionless FinFET structure with sub-5nm shell doping profile by molecular monolayer doping and microwave annealing

For the first time, a novel junctionless (JL) FinFET structure with a shell doping profile (SDP) formed by molecular monolayer doping (MLD) method and microwave annealing (MWA) at low temperature is proposed and studied. Thanks to the ultra thin SDP leading to an easily-depleted channel, the proposed JLFinFET can retain the ideal subthreshold swing (~ 60 mV/dec) at a high doping level according to simulations. Poly Si based JLFinFETs processed with MLD and MWA exhibit superior subthreshold swing (S.S. ~ 67mV/dec) and excellent on-off ratio (>10⁶) for both n and p channel devices. Threshold voltage (V_TH) variation due to random dopant fluctuation (RDF) is reduced in MLD-JLFinFETs, which can be attributed to the molecule self-limiting property of MLD on the Si surface and quasi-diffusionless MWA at low temperature. Our results reveal the potential of the proposed SDP enabling a JLFET showing reduced variation and outstanding performance for low power applications.