Impact of Ferroelectric Wakeup on Reliability of Laminate based Si-doped Hafnium Oxide (HSO) FeFET Memory Cells

摘要

The impact of the ferroelectric (FE) wakeup phenomenon on the reliability of fluorite structure-based laminated Si-doped hafnium oxide (HSO) FeFET memory cells is reported. The post wakeup cycling shows a strong change in the optimal program/erase (PG/ER) write conditions. A shift towards lower PG/ER switching conditions at a higher memory window (MW) is observed after wakeup cycling. Similarly, the cross wafer statistics for different FeFET dimensions shows a strong wakeup influence towards a lower variability and higher MW after wakeup. For the wakeup cycling different trends for amplitude and pulse width variation are observed. The increase in write pulse amplitude has limited impact whereas the number of wakeup cycles appears to be the driving factor. On the contrary, the write pulse width sweep (50-800ns) shows faster wakeup as the pulse width increases even on pristine devices. The FeFET area sweep shows a comparable wakeup behavior with a trend of higher shift window on larger devices. The high-temperature operation shows an initially lower MW and pronounced wakeup effect. On the other hand, the pyroelectric effect dominates at lower temperatures and leads to initially higher MW with an insignificant wakeup. The various factors associated with the FE wakeup effect are studied with insight into the changes in FeFET stack physics during wakeup cycling.