Probe-Dependent Residual Error Analysis for Accurate On-Wafer MOSFET Measurements up to 110 GHz

Advances in CMOS technology have enabled MOSFET with cutoff and maximum oscillation frequencies (ft and fmax) in the 400 GHz range, thus opening the path to CMOS-based applications at millimeter-wave (mm-wave) and sub-THz frequencies. Accurate compact models and therefore on-wafer MOSFET measurements at mm-wave frequencies and beyond become crucial for IC design at such high frequencies. However, accurate on-wafer measurement at these frequencies is a complex task requiring dedicating special care to calibration kit (calkit) design and characterization. This paper presents a complete and detailed parasitic correction procedure approach that demonstrates accurate corrected MOSFET measurements up to 110 GHz. It describes the custom calkit designed to perform ‘in-situ’ multiline Thru-Reflect-Line (mTRL) calibration. In this work, we compare different methods to evaluate the transmission line standards characteristic impedance and identify the best one by comparing the extracted series resistances of a MOSFET. The best method features frequency variations as low as <5% and <20% in source-drain and gate resistances, respectively, up to 110 GHz. Finally, by applying the most suited correction procedure to measurements of different RF probe technologies and comparing them to compact model simulations, we demonstrated high-accuracy FET measurements up to 110 GHz, thanks to an excellent agreement between the probe data and simulations, even in presence of probe-dependent residual errors.