Burn-in stressing effects on post-irradiation annealing response of power VDMOSFETs

The effects of pre-irradiation burn-in stressing on post-irradiation annealing response of power VDMOSFETs have been investigated. Threshold voltage rapid increase above its preirradiation value (rebound effect) and mobility increase up to the value somewhat higher than the one after irradiation have been observed during post-irradiation annealing. These phenomena occured with certain delay in pre-irradiation stressed devices. The underlying changes of gate oxide-trapped charge and interface trap densities have been calculated and analysed in terms of the mechanisms responsible for pre-irradiation stress effects.