Bulk 14-nm FinFET technology was irradiated in a heavy-ion environment (42-MeV Si ions) to study the possibility of displacement damage (DD) in scaled technology devices, resulting in drive current degradation with increased cumulative fluence. These devices were also exposed to an electron beam, proton beam, and cobalt-60 source (gamma radiation) to further elucidate the physics of the device response. Annealing measurements show minimal to no 'rebound' in the ON-state current back to its initial high value; however, the OFF-state current 'rebound' was significant for gamma radiation environments. Low-temperature experiments of the heavy-ion-irradiated devices reveal increased defect concentration as the result for mobility degradation with increased fluence. Furthermore, the subthreshold slope (SS) temperature dependence uncovers a possible mechanism of increased defect bulk traps contributing to tunneling at low temperatures. Simulation work in Silvaco technology computer-aided design (TCAD) suggests that the increased OFF-state current is a total ionizing dose (TID) effect due to oxide traps in the shallow trench isolation (STI). The significant SS elongation and ON-state current degradation could only be produced when bulk traps in the channel were added. Heavy-ion irradiation on bulk 14-nm FinFETs was found to be a combination of TID and DD effects.
Total ionizing dose response of 14-nm bulk-Si FinFETs has been studied with a specially designed test chip. The radiation testing shows evidence of interface trap build-up on 14-nm Bulk FinFET technologies. These defects created in the isolation layer give rise to a new radiation-induced leakage path which might lead to a reliability issue in CMOS technologies at or below the 14-nm node. TCAD simulations are performed and an analytical model for TID-induced leakage current is presented to support analysis of the identified TID mechanism. TCAD simulation and analytical model results are consistent with the experimental data.