Extraction of Effective Mobility from nMOSFETs With Leaky Gate Dielectric Using Time Domain Reflectometry

The effective mobility (μ
_eff
) of MOSFETs with ultrathin high-k gate dielectric (EOT = 0.85 nm) has been successfully extracted using a time domain reflectometry method. A ground-signal-ground-ground probe configuration is used to analyze the gate-to-channel capacitance (C
_gc
), gate-to-bulk capacitance (C
_gb
), and total gate capacitance (C
_g
) without a complex RF test structure. Using this method, the effective mobility can be extracted even in the presence of a high gate leakage current (~30 A/cm
²
) when the conventional split capacitance-voltage method using an impedance analyzer cannot be applied.