Two-dimensional methodology for modeling radiation-induced off-state leakage in CMOS technologies

A modeling approach using two-dimensional device simulations is presented, which enables the extraction of parameters for the radiation-induced parasitic MOSFET created at the edge of the shallow trench isolation (STI) oxide. With the model, one can estimate drain-to-source off-state leakage current (I/sub OFF/) resulting from build-up of oxide trapped charge (N/sub OT/). The impact of nonuniform N/sub OT/ build-up in the STI resulting from total ionizing dose (TID) exposure and external bias conditions is analyzed through volumetric simulations and compared to experimental data. Saturation for the off-state leakage current as a function of trapped charge is also investigated.