A physics-based numerical modeling of total ionizing dose effects in CMOS integrated circuits

A physics-based numerical model is proposed as a simulation tool to predict the total ionizing dose response of CMOS integrated circuits. The model includes the radiation-induced charge buildup within both the gate oxide of the standard transistors and the bird’s beak parasitic transistor due to LOCOS isolation method. The zero bias radiation response of standard MOSFETs is simulated, showing the difference between n- and p-channel transistors. For high dose levels, the charge buildup in the parasitic transistor leads to an increase of the off-state leakage current for nMOSFET. The radiation response of an inverter is shown as an example of the consequence this increment of the leakage current may cause to the simple CMOS circuit. The model showed to successfully predict the increment in the delay and the failure of the circuit for high absorbed doses.