Improved Immunity to Sub-Cycling Induced Instability for Triple-Level Cell Ferroelectric FET Memory by Depositing HfZrOₓ on NH₃ Plasma-Treated Si

Split-up effect caused by sub-cycling would change the coercive voltage (
$\text{V}_{\textrm {C}}$
) of a ferroelectric HfZrO
_x
(HZO) film by the induced local internal field due to oxygen vacancy (Vo) related behaviors and is detrimental to MLC operation. By depositing the HZO on NH
₃
plasma-treated Si, due to the high-quality SiN
_x
interfacial layer that reduces the amount of Vo in the HZO, the ferroelectric FET (FeFET) memory reveals a large memory window of 3.2 V by +6/-5 V with
$5 {\mu } \text{s}$
pulse width and much improved reliability against sub-cycling for multi-level cell (MLC, 2 bits/cell) operation than those without plasma treatment. The FeFET memory also for the first time displays the stable (threshold voltage)
$\text{V}_{\textrm {TH}}$
for each state for triple-level cell (TLC, 3 bits/cell) operation up to
$3\times 10^{\textrm {3}}$
cycles that meets the industry requirement under strict sub-cycling and exhibiting quadruple-level cell (QLC, 4 bits/cell) operation with desirable retention, ushering in new paradigms for advanced high-density memory applications.