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

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 V^th shift and off state drain current (I^off@V^g=0V) shift can recover after 1000sec post-radiation annealing. While the linear drain current (I^dlin) exhibits monotonically decrease except for the initial radiation phase. In contrast, the flash cell V^th shift halts immediately after radiation stops, and the V^th 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.