Evolution of the gate current in 32 nm MOSFETs under irradiation

Abstract

Radiation induced currents on single 32 nm MOSFET transistors have been studied using consecutive runs of 16 O at 25 MeV. The main feature is the generation of current peaks ? in the gate and channel currents ? due to the collection of the electro?hole pairs generated by the incident radiation runs. It has been observed that the incident ions cause damage in the dielectric layer and in the substrate affecting the collection of carriers, and hence the radiation-induced current peaks. It has been find out a decrease of the current peak due to the increase of the series resistance by non-ionizing energy loss in the semiconductor substrate, and an increase of the leakage current due to defects in the gate oxide by ionizing energy loss. For low levels of damage in the gate oxide, the main feature is the shift of the VTH. Hot carriers heated by the incident radiation in the depletion region and injected in the gate oxide cause the change of the VTH due to electron or hole trapping for n- or p-channel respectively. The overall results illustrate that these effects must be taken into consideration for an accurate reliability projection.