Full understanding of hot-carrier-induced degradation in STI-based LDMOS transistors in the impact-ionization operating regime

Hot-carrier-injection (HCI) effects are studied in n-channel rugged LDMOS transistors in high current-voltage biases, by monitoring the linear and saturation regimes. Experimental data reveal that the degradation effects responsible for the HCI parameter drifts are mainly localized in the channel and in the drift region close to the drain. The temperature dependence of the HCI degradation is analyzed to gain understanding in the underlying physics. TCAD simulations aimed at investigating the sensitivity of the current shift to different local distributions of trapped charges have been carried out, and a compact model for the linear current has been developed for the purpose of extracting the effective-mobility degradation in the channel and the charge trapped in the drift region. The overall methodology represents a new approach to the HCI analysis suitable for device structures with STI in the drain extension region.