The feasibility of full split C-V method in ultra-thin body and BOX (UTBB) FDSOI devices is demonstrated, emphasizing the usefulness of gate-to-bulk capacitance. The split C-V measurements carried out on both gate-to-channel and gate-to-bulk mode are shown to be consistent with TCAD simulation. This enabled us to propose an improved parameter extraction methodology for the whole vertical FDSOI stack from gate to substrate using back biasing effect. (C) 2014 Elsevier Ltd. All rights reserved.