Investigation of the total dose response of partially depleted SOI nMOSFETs using TCAD simulation and experiment

We have analyzed total ionizing dose response of partially depleted SOI nMOSFETs fabricated in a 0.13 μm commercial technology assisted by TCAD simulation. Using TCAD tools, the ionizing radiation-induced damages in buried oxide and shallow-trench oxide are investigated separately. It is shown that back transistors are radiation tolerant up to 1 Mrad (Si) for core nMOSFETs even under the worst case whereas back transistors of I/O devices are 100 krad (Si) due to lower doping concentration. In addition, the enhanced total dose degradation with applied gate bias is attributed to more charge trapped in shallow-trench oxide. 2D cross section electrical simulation schematically illustrates the evolution of charge trapping in buried oxide and shallow-trench oxide. It is found and verified that parasitic corner transistor located at the bottom of swallow-trench oxide plays a critical role on the radiation hardness of partially depleted SOI nMOSFETs.