The effect of shallow trench isolation (STI) topology, sidewall doping and layout-related stress on radiation-induced leakage current
Rezzak, Nadia
:
2010-04-16
Abstract
Scaling of gate oxides in bulk complementary metal–oxide–semiconductor (CMOS) devices to thinner dimensions has reduced the significance of threshold-voltage shifts due to total-ionizing dose (TID) radiation-induced charge buildup in the thin oxides. As a result, the dominant TID effect in most CMOS technologies is now leakage current produced by charge buildup in the shallow-trench isolation (STI).
In this thesis, the sensitivity of radiation-induced source-drain leakage to the amount of recess in STI of CMOS technologies is studied. The impact of the doping profile along the STI sidewall on the magnitude of the leakage current is quantified, and finally layout-related stress effects on TID-induced leakage current were investigated. The TID-induced leakage current of deep submicron MOSFETs increases with increasing active-to-isolation spacing. Mechanical stress reduces impurity diffusion at the STI sidewall, affecting the TID sensitivity. The sensitivity of the radiation-induced leakage current to these parameters provides insight into how process variability is manifested as variations in the radiation response.