Impact of lateral isolation oxides on radiation-induced noise degradation in CMOS technologies in the 100-nm regime

Degradation mechanisms associated to lateral isolation oxides are discussed to account for total ionizing dose effects on the noise performance of 90 nm and 130 nm CMOS devices and for their dependence on geometry and operating conditions. In NMOSFETs with a conventional open layout, after irradiation the parasitic transistor at the device edges turns on and contributes to the total device noise. The paper provides a model to help understanding the impact of this radiation-induced noise contribution on white and 1/f noise terms. The different behavior of NMOSFETs in the two examined technology nodes is analyzed in this framework, and design criteria to reduce noise degradation in irradiated devices are discussed.