Forming Process in BEOL Oxide Channel Ferroelectric FET

In this work, we report the observation of a forming step in the back-end-of-line (BEOL) oxide channel ferroelectric FET (FeFET). This behavior has typically been neglected but is deeply rooted in the polarization switching mechanism. It could support one-time programmability (OTP) on top of the typical programmable operation. We show that: 1) the forming step originates from insufficient back-switching of polarization during negative reset due to the lack of hole supply in the n-type doped wide-bandgap channel, preventing the high threshold voltage ( ${V} {_{\text {TH}}}$ ) state from returning to the pristine state; 2) this behavior is present in both long and scaled gate length FeFETs, indicating a general behavior and the possibility of scalable OTP memory; and 3) with proper treatment of the source/drain inner fringe field, an oxide channel BEOL FeFET physical model adapted from the virtual-source (VS) model is developed, which can reproduce the forming behavior.