Inversion MOS capacitance extraction for high-leakage dielectrics using a transmission line equivalent circuit

Accurate measurement of MOS transistor inversion capacitance with a physical silicon dioxide thickness Less than 20 Angstrom requires correction for the direct tunneling leakage. This work presents a capacitance model and extraction based on the application of a lossy transmission line model to the MOS transistor. This approach properly accounts for the leakage current distribution along the channel and produces a gate length dependent correction factor for the measured capacitance that overcomes discrepancies produced through use of previously reported discrete element based models. An extraction technique is presented to determine the oxide's tunneling and channel resistance of the transmission line equivalent circuit. This model is confirmed by producing consistent C-ox measurements for several different gate lengths with physical silicon dioxide thickness of 9, 12, and 18 Angstrom.