Effect of Si-implantation Induced Nanocrystals on Reducing the Oxide and Interface Traps Densities of PD SOI MOSFET Under Total-dose Irradiation

I-V characteristics of PD (partially-depleted) NMOS transistors with GAA (gate-all-around) structure fabricated on SIMOX which is hardened by silicon ions implantation were discussed under total-dose irradiation of three bias conditions. It is found experimentally that irradiation-induced threshold voltage shift DeltaV_th and leakage current of hardened transistors was greatly reduced, comparing to control ones. The effect of total dose on the buildup of net positive oxide traps DeltaN_ot and interface traps DeltaN_it are also analyzed using the charge separation method, indicating that hardened transistors have much less DeltaN_ot and DeltaN_it than control ones. The reduction of DeltaV_th and Delta_ot are due to the formation of entities in the BOX (buried oxide) that have a large electron capture cross section. PL (photoluminescence) studies on ion-implanted thermal oxides demonstrate that these entities are Si nanocrystals which increases with implantation dose