Characterization of Hot-Carrier-Induced RF-MOSFET Degradation at Different Bulk Biasing Conditions From S-Parameters

A method to evaluate hot-carrier-induced degradation in MOSFETs and incorporating the corresponding effect into the RF small-signal model is presented. The method is based on the controlled and gradual degradation of a common-source configured RF-MOSFET by applying a high drain-to-source dc voltage. For this purpose, the electrical stress is monitored through the current measured at a bulk terminal separated from the RF pads used to collect the S-parameters, which allows the precise definition of the stress condition. The small-signal parameters are determined from measured S-parameters for a fresh device and as degradation occurs to quantify the corresponding dependence on time. Exhaustive measurements and parameter extractions point out the impact of hot-carrier-injection (HCI) stress on both the intrinsic and extrinsic elements, which show an expected trend described by a power equation. To verify the validity and consistency of the method, S-parameter model-experiment correlations are carried out before and after HCI stress when using the implemented models and extracted data. In this way, an excellent agreement between simulated and experimental data is achieved.