I. Introduction
As operation voltage () scaling lags behind geometrical scaling, long-term stability becomes an issue due to increased electric field in field effect transistors (FETs). This increase induces several degradation mechanisms such as stress induced leakage current (SILC), hot carrier injection (HCI), and bias temperature instability (BTI). In space applications, ionizing radiation degradation such as total ionizing dose (TID) is a critical issue. The TID becomes particularly important in chip scale satellites and wafer scale spacecraft [1], where conventional metal radiation shielding can nullify their lightweight benefit for efficient launching and propulsion. Consequently, a method to increase the long-term stability in post-processed devices is of great interest.