Methodology for Flatband Voltage Measurement in Fully Depleted Floating-Body FinFETs

Among the novel methods for flatband voltage (V_fb) measurement, we demonstrate that a gate-leakage-based technique is the most suitable for measuring V_fb in floating-body MOSFETs with ultrathin gate dielectrics. Starting from carrier separation experiments on planar MOSFETs, we show the universality of the gate conduction mechanism dependence on band alignment for both n- and p-FETs. We demonstrate that metrics based on the gate leakage (either its valence-band electron-tunneling component or its first-order derivative) reflect this dependence and allow equivalent-oxide-thickness-independent V_fb quantification. This dependence is also valid for high-k and capped gate dielectrics, whereas their gate conduction mechanism is dominated by direct tunneling. To illustrate, we extract gate-leakage-derivative-based metrics and measure V_fb of TaN and TiN gate electrodes in multiple-fin FETs integrated on silicon-on-insulator.