Showing papers by "John W. Palmour published in 2022"

Gate Bias Effects on SiC MOSFET Terrestrial-Neutron Single-Event Burnout

Abstract: Power devices are susceptible to failure by terrestrial neutron single-event burnout (SEB) while in the high-voltage blocking state and above a VDS threshold for that device. Typically, the SEB failure rate is measured at a high blocking voltage, with the source and gate at ground potential. Here the effect of a negative gate bias, commonly applied during MOSFET switching to the blocking state, on the SEB failure rate is examined. It is observed that the SEB failure rate is only weakly dependent on the negative gate bias, because it does not significantly affect the peak field in the drift region where avalanche breakdown is initiated. A negative gate bias of -8VGS in the device blocking state at 1100VDS only results in a 6% increase in the MOSFET SEB failure rate.

Negative Gate Bias TDDB evaluation of n-Channel SiC Vertical Power MOSFETs

Abstract: With the steep expansion of the n-type 4H-SiC power metal-oxide-semiconductor field-effect transistor (MOSFET) market space, gate oxide reliability is gaining more and more attention. Although there exist several reports dealing with the bias temperature instability (BTI) under both positive and negative gate biases, gate oxide lifetime evaluations predominantly focus on positive gate bias time-dependent dielectric breakdown (TDDB) stresses for n-channel SiC MOSFETs. In this work we address that gap. From the negative gate bias TDDB data measured at 175 °C and at a gate oxide electric field of about 4 MV/cm, an intrinsic lifetime of 1E8 hours has been predicted, which closely matches with the results obtained from similar devices under positive gate stress. Also, in this work the correlation between failure location in a MOSFET unit cell and the failure signatures during TDDB stress have been established, and an explanation from a device physics standpoint has been provided. The identification of the failure location in the unit cell from in-situ gate leakage data without the need of physical failure analysis can turn out to be key during the early phase of a new process development activity.

DC and RF Reliability Assessment of 5G-MMW capable GaN HEMT Process (Invited)

Abstract: Owing to its high power, high efficiency, high gain and high frequency capabilities RF-GaN technology has not only dominated satellite, aerospace and telecom industry but also been tapped as the most promising candidate for 5G technology extension to millimeter wave (MMW) applications. Excellent device performances with output power density (Pout) exceeding 3 W/mm and peak power added efficiency (PAE) above 35 % have been demonstrated by Wolfspeed's 5G-MMW capable 28 V, 150-nm gate length (V5) GaN on SiC technology. In this work we show the comprehensive DC (both on and off state) and RF reliability assessment and lifetime projection (both DC and RF) of such MMW capable 28 V rated 150-nm gate length process technology (G28V5). The on-state and off-state results coupled with the reliability without hermiticity (RWOH) capability and intrinsic reliability assessment up to 31.5 GHz demonstrate the maturity and reliability of V5 technology as a true candidate for MMW applications.