Influence of poly region extended into field oxide on total ionizing dose effect for deep submicron MOSFET

Deep submicron technology devices with different width/length were exposed by gamma ray irradiation. Different total ionizing dose (TID) effects were observed for the wide and narrow channel device. Large increase of off-state leakage was observed for the wide channel device under radiation. However, insignificantly increase of off-state leakage was observed for the narrow channel one. The simulation result of potential distribution in the shallow trench isolation (STI) has shown that the influence of poly region extended into field oxide on the device's radiation response. The oxide trapped charge in the top and down region of the STI plays an important role in the different TID responses. A negative substrate bias during irradiation can give us more information about the charge distribution along the STI sidewall. By introducing non-uniform charge along the STI sidewall in the three dimension (3D) simulation, good agreement between the experiment and simulation result is demonstrated.