Total dose effects on the shallow-trench isolation leakage current characteristics in a 0.35 mu m SiGeBiCMOS technology

The effects of gamma irradiation on the Shallow-Trench Isolation (STI) leak age currents in a SiGe BiCMOS technology are investigated for the first tim e, and shown to be strongly dependent on the irradiation gate bias and oper ating substrate bias. A positive irradiation gate bias significantly enhanc es the STI leakage, suggesting a strong field assisted nature of the charge buildup process in the STI. Numerical simulations also suggest the existen ce of fixed positive charges deep in the bulk along the STI/Si interface. A negative substrate bias, however, effectively suppresses the STI leakage, and can be used to eliminate the leakage produced by the charges deep in th e bulk under irradiation.