Total ionizing dose effect investigated by in-situ measurements for a 65nm flash technology

Abstract

In-situ measurement was introduced to characterize the total ionizing dose (TID) radiation response of high voltage (HV) nMOS devices and memory cells in a 65nm Flash technology. Device parameter shifts during both radiation and subsequent relaxation/annealing phases was monitored in real-time. For HV nMOS device, about 20% of the Vth shift and off state drain current (Ioff@Vg=0V) shift can recover after 1000sec post-radiation annealing. While the linear drain current (Idlin) exhibits monotonically decrease except for the initial radiation phase. In contrast, the flash cell Vth shift halts immediately after radiation stops, and the Vth keeps almost constant thereafter. The distinct difference of TID response behavior was attributed to different TID physical mechanisms of two types of devices. The work provides a new perspective for the short term TID response of Flash technologies.