Gate Damages Induced in SiC Power MOSFETs During Heavy-Ion Irradiation—Part II

Abstract

This article presents the results of a 2-D finite element simulation study of the gate damages induced by heavy-ion irradiation in SiC power metal-oxide-semiconductor field-effect transistors (MOSFETs). The time evolution of the electric field in the gate oxide is studied. Two effects are investigated: the first is associated with the charge deposition in the SiC portion of the MOSFET, with the time evolution studied using the 2-D finite element simulator; the second one results from holes generated during the ion transit, trapped in the gate oxide after the fast electrons have been quickly swept away by the electric field. Two different techniques have been combined for estimating the hole concentration in the gate oxide: the well-known recombination rate was modified to consider the trapped charge yield, as was recently done to better interpret single event gate rupture (SEGR) failure of silicon power MOSFETs. Under ion irradiation test conditions at which the gate damage experimentally starts to be observed, we demonstrate that, because of the ion impact, regardless of the ion linear energy transfer (LET), the peak value of the electric field in the gate oxide becomes practically equal to the oxide breakdown field (~12-15 MV/cm). Moreover, we show that simulations can be used to predict the test conditions at which gate damage starts to appear as a function of LET and the range of heavy ions used in the irradiation experiments.