Lateral Capacitance–Voltage Method of NanoMOSFET for Detecting the Hot Carrier Injection

In this paper, the dependence of the capacitance of lateral drain–substrate and source–substrate junctions on the linear size of the oxide trapped charge in MOSFET is simulated. It is shown that, at some range of linear sizes of the trapped charge, the capacitance of lateral junctions linearly depends on the linear size of the trapped charge. The dependence of the difference between drain–substrate and source–substrate capacitances on the linear size of trapped charges is also simulated. The revealed dependence can be used in measurements to estimate the linear size of oxide trapped charges induced by hot carrier injection, which can occur during MOSFET operation at defined conditions.

NBT stress and radiation related degradation and underlying mechanisms in power VDMOSFETs

In this paper we provide an overview of instabilities observed in commercial power VDMOSFETs subjected to irradiation, NBT stress, and to consecutive exposure to them. The results have indicated that irradiation of previously NBT stressed devices leads to additional threshold voltage shift, while NBT stress effects in previously irradiated devices depend on the gate bias applied during irradiation and on the total dose received. This points to the importance of the order of applied stresses, indicating that for proper insight into the prediction of device behaviour not only harsh conditions, but also the order of exposure have to be considered. It has also been shown that changes in the densities of oxide trapped charge and interface traps during spontaneous recovery after each of applied stresses can be significant, thus leading to additional instability, even though the threshold voltage seems to remain stable, pointing to the need for clarifying the responsible mechanisms.

Power lateral pnp transistor operating with high current density in irradiated voltage regulator

The operation of power lateral pnp transistors in gamma radiation field was examined by detection of the minimum dropout voltage on heavily loaded low-dropout voltage regulators LM2940CT5, clearly demonstrating their low radiation hardness, with unacceptably low values of output voltage and collector-emitter voltage volatility. In conjunction with previous results on base current and forward emitter current gain of serial transistors, it was possible to determine the positive influence of high load current on a slight improvement of voltage regulator LM2940CT5 radiation hardness. The high-current flow through the wide emitter aluminum contact of the serial transistor above the isolation oxide caused intensive annealing of the positive oxide-trapped charge, leading to decrease of the lateral pnp transistor's current gain, but also a more intensive recovery of the small-signal npn transistors in the control circuit. The high current density in the base area of the lateral pnp transistor immediately below the isolation oxide decreased the concentration of negative interface traps. Consequently, the positive influence of the reduced concentration of the oxide-trapped charge on the negative feedback reaction circuit, together with the favourable effect of reduced interface traps concentration, exceeded negative influence of the annealed oxide-trapped charge on the serial pnp transistor's forward emitter current gain.